The Hottest Place on Earth

by Conroy

Burning Death Valley

For those of you who, like me, are interested in the extremes of our natural world, there is a new hottest place on Earth: Death Valley, California.¹ The record was set in the small town of Furnace Creek and now stands at a roasting 134 degrees Fahrenheit (56.7 degrees Celsius). What’s unusual about this record is that it wasn’t set this month or even this year, but way back in July 1913 (99 years ago). What’s even more unusual is that the new record is lower, less scorching², than the previous record of 136 degrees measured (not quite as) way back in 1922 at El Aziziya, Libya. As I’ve written about before, this 90-year-old record has been dubious from the start, and now the World Meteorological Organization (WMO) has invalidated it.

Just to be clear, the record for highest temperature refers to air temperature measured in the shade. Temperatures in the sun can rise well above 134 degrees and ground temperatures heated by the sun can be higher still, almost to the boiling point. (In comparison, the hottest bodies of water tend to be merely warm, like bathwater.³) Getting back to El Aziziya, a quick glance at the map shows that it is located not deep in the Sahara where one might expect a record temperature to be recorded, but just 25 miles from the cool Mediterranean and its moderating breezes. This seems like an unusual place for the planet’s high temperature to occur. The WMO determined that the El Aziziya temperature was the result of the weather station being improperly placed on a black tarmac surface with the thermometer too close to the ground, and thus artificially increasing the measured high temperature. Further, the measurement was probably misread by an inexperienced record keeper. High temperatures measured before and after 1922 didn’t come close the record, lending support that the 1922 reading was an unlikely anomaly. The upshot is that El Aziziya no longer holds the record.

The Crucible of Death Valley
Death Valley is really hot. On July 11 this year the temperature peaked at 128 degrees, not exactly threatening the record, but close enough to tell you that in summer Death Valley is indeed a burning, fiery furnace, a sun’s anvil.⁴ But Death Valley is a place of extremes. Not only is it hot, but it’s also the lowest point in the Western Hemisphere, 282 feet below sea level, and the driest place in North America, receiving a little more than two inches of precipitation each year. It’s situated in eastern California and flanked on the east and west by high mountain ranges.⁵ Moisture from the Pacific Ocean is squeezed out of the air by the mountain ranges to the west of Death Valley, and the dry air heats as it sinks under cloudless skies, baking the desert floor. If your idea of hell is flaming heat, then summer in Death Valley is hell.⁶

There is a peculiar type of individual that chooses to test themselves in this crucible. Each year 80 or so runners participate in the Badwater Ultramarathon, which is described by the race organizers as the “world’s toughest foot race.” Ultramarathoners are a rare lot. These are endurance runners who take on races of 50, 75, 100 or more miles, running hour-upon-hour (and sometimes day-after-day) through exhaustion, pain, injury, and mental and psychological distress. For the runners, these races become tests of the body and soul. That’s why ultramarathoners will gulp thin air at high altitudes or suffer through frostbite in freezing winter cold or cross the cauldron of Death Valley in July. For most people, the effort required for an ultramarathon passes over the line from personal test and fitness goal to deranged masochism.⁷

A lonesome Badwater ultramarathoner

And it’s a rare ultramarathoner who can complete the Badwater race within the allotted 60 hours. To do so, you have to run over a 135-mile course across Death Valley and then halfway up the slope of nearby Mount Whitney. The race requires you to grapple with not only the deadly summer heat but lung-busting thin air at high altitude. So how does Death Valley treat these runners? In his winning debut, legendary ultramarathoner Scott Jurek stopped periodically to submerse himself in a man-sized cooler filled with ice water (each runner is attended by a team – the race itself offers no support – with food, water, medical help, emotional and psychological sustenance, and all other logistical support). The heat off the road can reach 150 degrees and actually melt shoe soles and burn feet and calves. The over-like air forces the body into a panic and blood to the extremities, trying in vain to keep the runner’s core from overheating. Dehydration and severe gastro-intestinal distress are par for the course. The conditions are so intense, and the body and mind so stretched, that runners often hallucinate, seeing mirages rise from the shimmering desert. Sounds pleasant doesn’t it?

Very few of us will ever run the Badwater race (or anything similar), but the summer conditions in Death Valley are so extreme that if you were left there with no water or relief from the sun, you’d be dead within a day or two.⁸

A Hotter Place?
No place on earth is hotter than Death Valley in summer, but it’s well north of the tropics and so is actually very mild in the winter. The average December temperature at Furnace Creek is a cool 52 degrees, and the record low is -9 degrees F (-22.8 C). There are other places on Earth that never get a respite from the high heat. Perhaps the hottest place on the planet by average temperature is found Dallol in remote far northern Ethiopia.

Dallol, like Death Valley, sits at the bottom of a deep depression, about 430 feet below sea level, in a dry desert. But unlike Death Valley, Dallol’s latitude is well within the tropics (just 14 degrees north) and so it cooks under an intense sun all year long. There was a salt mining operation at Dallol in the early 1960s. During that time the average yearly temperature was a suffocating 94 degrees, and the average daily high was 106 degrees. Today Dallol is uninhabited, the salt operation long since abandoned. It’s a place that, like Antarctica, is unfit for man.

Death Valley is home to only a few thousand people. But there are some major cities that experience extreme heat. Here are the record high temperatures for some of these cities: Kuwait, Kuwait (128), Khartoum, Sudan (127), Riyadh, Saudi Arabia (126), Jeddah, Saudi Arabia (126), Basra, Iraq (126), Phoenix, Arizona (122), Baghdad, Iraq (122), Bahrain (122), Doha Qatar (122), Karachi, Pakistan (118), Dubai, UAE (117), Tucson, Arizona (117), Las Vegas, Nevada (117), and Murcia, Spain (117).

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NOTES:

1. It’s more accurate to note that there is a new highest measured temperature on Earth because there’s no way to verify that the record measured air temperature at one weather station is a record for any time across the entire planet.

2. It would be inappropriate to write that the new record is “colder” than the previous record.

3. The warmest body of water (or the warmest part of the warmest bodies of water) is hard to determine, but candidates include the Red Sea, Persian Gulf, Indian Ocean, and Caribbean Sea. This of course ignores small geo-thermally heated bodies of water like geysers and natural hot springs.

4. Film buffs may recognize these descriptions from dialogue spoken in that ultimate desert movie (and cinema masterpiece) Lawrence of Arabia.

5. Here’s a neat piece of geographic trivia: Death Valley, the lowest place in North America is located just 85 miles from Mount Whitney (summit elevation: 14,505 feet), the highest mountain in the contiguous United States.

6. My idea of Hell is closer to Dante’s, a dark frozen waste. So for me hell on earth is to be found in coldest part of Antarctica, like for instance, the Vostok Station. But my ideas aside, summer in Death Valley is hellish.

7. I can recommend Christopher McDougall’s book Born to Run if you’re interested in learning more about what these races entail and what type of personality they attract.

8. The name of the place doesn't lie.

Sinking Cities

by Conroy

Baltimore flooded by Hurricane Isabel

Are America’s coastal cities facing a losing battle against the sea? Consider these facts from cities all along the U.S. East Coast: In Galveston, Texas, a long sea wall shields the city from the Gulf of Mexico. The sea wall worked for a century, but in 2008 the storm surge from Hurricane Ike overtopped the wall and flooded the adjacent streets. In the early 1980s Miami-Dade County spent $50 million to rebuild the eroding shore line of Miami Beach. Similar projects, officially termed “beach nourishment”, are common all along the Atlantic seaboard¹. In some precariously narrow sections of Hatteras Island, North Carolina, far off the mainland in the state’s Outer Banks, sand bags line both sides of the state route 12 to keep the Atlantic on one side and Pamlico Sound on the other from splitting the island. Back in 2003 when Hurricane Isabel roared up the East Coast, the island was split and an emergency project was required to stop the erosion and prevent the split from becoming permanent. Hurricane Isabel continued its movement up the East Coast flooding coastal areas of Virginia and as it moved inland its powerful storm surge funneled water up the Chesapeake Bay causing widespread flooding in coastal Maryland, and putting Baltimore, including downtown, under several feet of water. The flooding even extended far up the tidal Potomac to Washington, D.C. In 2011, the storm surge from Hurricane Irene flooded parts of Brooklyn and lower Manhattan. Further north, Nantucket Island off of Cape Cod is literally eroding into the sea, taking pricey homes with it.

As these examples above demonstrate, being next to the sea has its dangers, and fighting the long-term trend of beach erosion and flooding are never-ending expensive battles. This situation is only going to get worse if a planet-wide trend continues: rising sea levels. Consider that just along the Atlantic and Gulf coasts Boston, New York, Philadelphia, Baltimore, Washington, Jacksonville, Miami and Southeast Florida, Tampa Bay, and New Orleans are situated at least in part at sea level. And it’s not just major metropolitan areas that are at risk, the low-lying shores of the Houston shipping channel, just inland from Galveston, are home to one of the nation’s largest ports and lined with the nation’s largest concentration of petroleum refining plants. Are all of these areas destined to be inundated over the next century?

Sea Levels Rising
Of course the first thing that has to be answered is: Are sea levels actually rising? And to answer that, we need to understand what sea level is. Sea level is harder to define than it may seem because of course the flowing, undulating sea never seems to have one level. However, the most basic definition is the average surface elevation of the oceans when surface fluctuations, like high and low tides are averaged out. This seems like a reasonable definition but it nevertheless can be hard to pin down. Note that the average sea level of the Atlantic end of the Panama Canal is nearly eight inches lower than at the Pacific end. Still, it’s fair to say that there is a local “sea level” for all places where land meets tidal water. Historically these levels have been measured from set gauges on land, and more recently satellites have been used to observe global sea levels.

The results of these measures seem to confirm that sea levels are indeed rising all over the world. According to the Intergovernmental Panel on Climate Change (IPCC)², global sea levels have been rising by about 1.8 millimeters per year (mm/yr.). If this estimate is in any way accurate, and indicative of a continuing trend (and not a rate that may slow or even reverse in the near future), there’s probably no need for immediate panic. At this rate it would take about 555 years for global sea levels to rise by one meter or about 170 years to rise one foot. This is hardly a catastrophic rate of increase. However, rising sea levels, whatever the rate, do pose an obvious risk to coastal areas. And many estimates, including those by the National Oceanic and Atmospheric Administration (NOAA), put the annual sea level rise much higher than the IPCC.

But what causes sea level to change? On geologic timescales, ocean bottom elevations and plate tectonics play major roles. These occur so slowly that they don’t affect us. More important are short term causes like tides, onshore winds, atmospheric pressure, surface water temperatures, evaporation, precipitation, river runoff, and in extreme cases major storm surges and tsunamis. On the longer term sea levels can change because glaciers and ice caps shrink or expand. In the first case, melt water is freed from the land and adds to the volume in the sea. In the latter case, water is trapped in ice and global sea levels drop. Another long term trend is changes in land elevation due to groundwater depletion, erosion, or general geological subsidence. But it’s the melting glaciers and ice caps that have gathered most attention in recent decades, the result, many will claim, of rising global temperatures, which is in turn the result of man-made effects to the environment.

Melt water on the Greenland Ice Sheet

Man-made or natural, rising temperatures will melt snow and ice. If the entire Greenland Ice Cap were to melt, global sea levels could rise by as much as 24 feet. If the entire Antarctic Ice Cap were to melt global sea levels would rise by 200 feet. These are extremely remote possibilities, Greenland and Antarctica are really cold places and it would take many thousands of years for them to melt. And Arctic sea ice melting would have a negligible effect on sea levels because these ice packs are already floating on the sea. More likely is increased melting of ice on the periphery of Greenland and Antarctica, which could still result in several feet of sea level rise. Also, if sea surface temperatures increase, water density decreases and its volume increases. So higher sea temperatures result in higher sea levels irrespective of the contribution of more water (melted ice). It’s worth noting that global temperatures haven’t increased over the last dozen or so years, which is directly contrary to the predictions of climate models. If global temperatures do stabilize then sea water temperatures and ice cap/glacier melting may not be as significant an issue as many fear.

Now I don’t know if or how much global sea levels may be rising. Like all earth systems, the various components that affect sea level are complicated and combine in unexpected ways. For example, increasing global temperatures will lead to increased precipitation, which, if it falls in the polar regions like Antarctica, will actually increase the thickness of the ice caps and the amount of impounded water, which would lower global sea levels. However, higher temperatures should result in greater calving and icebergs breaking away from the subpolar regions, which would raise global sea levels. How might these two trends interact and which is greater?³ When you consider all of these components there has to be question of how measurements of these global trends can even be made and how accurate models of these global systems can be. Let alone what predictions for future developments are possible.

It’s also worth noting that many of the flooding examples cited at the beginning of this post were the result of major storms, which are not in themselves indicative of sea level rise. Never in my memory had Baltimore flooded from the sea like in 2003, and the Galveston sea wall had stopped all storms, including hurricanes, for a century. There’s plenty of room for debate about whether American cities face an impending crisis from rising sea levels.

Nevertheless, even if the global climate doesn’t warm appreciably over the next century, America’s coastal cities would be negligent to not prepare for rising sea levels and ever more frequent flooding. Sea levels appear to be rising slowing but consistently and this can’t be ignored. And as we consider coastal flooding, we should first turn from the U.S. East Coast to an ancient city on the Mediterranean.

The Perfect Climate - Part 5

by Conroy

Rio, unsurprisingly, has one of the best climates in the world

I spent the first four parts of this series exploring my climate ranking system and applying it to American cities in search of the "perfect climate". Now it’s time to expand the rankings to the whole world. Below I’ve ranked 150 cities [1] using both my original formula, which favors warm places, and the alternative formula presented in Part 4, which favors consistently temperate locations.

This is the fifth post in my “Perfect Climate” series. To check out the first four, use the following links: The Perfect Climate – Part 1 The Perfect Climate – Part 2 The Perfect Climate – Part 3 The Perfect Climate – Part 4 Also check out Conroy’s Perfect Climate Rankings page.

 As a reminder, warm cities are places with annual mean temperatures in the mid to upper 70s (or higher) and little seasonal variance. Examples include Miami, Rio de Janeiro, and Bangalore, India. Temperate cities are places with annual mean temperatures in the mid 60s (no higher) and little seasonal variance, and especially no really hot months. Examples include San Diego, Mexico City, and Cape Town, South Africa. I’m presenting dual rankings because these preferences seem to predominate when it comes to climate taste. For both approaches, cold cities fare poorly.

One thing to note regarding the “warm cities” ranking, in my original formula I assumed that the higher the annual mean temperature the better. I was examining American cities the warmest of which is Honolulu, Hawaii with an annual mean of 77.5 degrees. However, when I expanded my rankings to encompass all the world’s cities, I ran into a problem: much of the Earth is very hot. Many cities across Africa and Asia have annual mean temperatures that exceed 80 degrees. While I enjoy warm conditions, even I have to admit that there’s an upper limit above which the climate grows too hot. I decided to modify my original formula to penalize cities where the annual mean temperature exceeds 78 degrees [2]. This adjustment works the same as the temperature penalty applied in the alternative (temperate) climate formula for cities with annual mean temperatures above 65 degrees (see Part 4).

The World’s Climate
Before jumping to the actual rankings, I'll note a few general impressions from my review of climates for hundreds of places in all parts of the world.

Latitude and elevation combine to give Nairobi a pleasant climate

• Large portions of South America, Africa, and Asia are located at low latitudes but relatively high elevations. This combination of tropical locations perched well above sea level is a magic formula for a favorable climate. The tropical latitude results in consistent solar radiation throughout the year, which means little temperature variance, but the higher elevations moderate the temperature. Cities in these zones include Nairobi, Sao Paulo, and Bangalore, India. Each boasts a climate that would be far hotter (and far less bearable) if located near sea level.
• It’s surprising how few large cities are located in really cold places. Only six cities experience mean low temperatures in the single digits (F) during one or more winter months: Minneapolis, Minnesota, Ottawa, Montreal, and Edmonton, Canada, and Shenyang and Harbin, China. Indeed, Harbin (China's tenth largest city), in the far northeast of China right on the edge of Siberia, is the only major global city to experience mean low temperatures below zero (F) for any month of the year. It’s appropriately nicknamed the “Ice City”, and the winter cold there is worse than in Arctic places like Nome, Alaska. This relative paucity of large cities in places with harsh winters is another demonstration that the great majority of people the world over choose not to live in cold climates.
• Conversely, cities with average high temperatures above 100 degrees during one or more summer months are common across the American southwest, Saharan Africa, the Middle East, and South Asia. The highest monthly mean temperature for any major city belongs to Baghdad, Iraq where the July high is a heat-stroke-inducing 111 degrees. That’s nearly as hot as Death Valley during high summer. Other "hot" cities include Phoenix, Riyadh, Delhi, and Khartoum. In fact, the capital of Sudan has the highest annual mean temperature of any major city at 85.8 degrees. (It's worth noting that I developed this climate system thinking of the U.S. where air conditioning is ubiquitous. That's certainly not the case through the "hot" world, so the warm rankings should be considered with that in mind; warm may not be so pleasant where it can't be escaped.)
• Perhaps the continent with the most consistently superb climate is South America. All of that continent’s major cities score well on both the warm and temperate rankings. And of all nations, Brazil’s big cities boast almost universally excellent climates. This is also true of the other large southern hemisphere country, Australia, where all of its large cities also have friendly climates. This is a major contrast to the large nations of the northern hemisphere that are either cold (Canada and Russia) or feature widely varying climates (U.S. and China).
• If you’re interested in finding unvarying temperatures, then follow the Equator. Quito, Ecuador, Manaus and Belem, Brazil, Male in the Maldives, Kuala Lumpur, Singapore, and Brunei all lie on or near the Equator and are among the relatively short list of cities that have annual temperature variances of less than 3 degrees.
• Finally, it’s interesting to compare the most extreme climate on Earth to my climate rankings. Russia’s Vostok Station in Antarctica is renowned as the coldest place on the planet, the Pole of Cold [3]. The lowest ever measured surface temperature of -128.6 degrees was recorded there in 1983. The average August low temperature is -97 degrees, and it earns a climate score of -105. The temperatures at Vostok are comparable to the surface of Mars in winter. It puts things into perspective when evaluating the “perfect” and “terrible” climates across the globe. Harbin's climate is far closer to sunny Rio de Janeiro's than it is to interior Antarctica.

Ice sculptures in Harbin, the world's coldest big city

Now on to the rankings.

The Perfect Climate - Part 4

by Conroy

Do you prefer the weather of warm Miami or...

Ask yourself this question: What city has a better climate Miami or San Francisco? Anyone that’s read this blog and in particular my earlier posts analyzing “the perfect climate” will know that I favor the heat and sunshine of South Florida over the consistent cool of Northern California. However, I was in Florida last week, first in Orlando and then in Fort Lauderdale, and in keeping with what has been a remarkably warm 2012 for the eastern two-thirds of the United States, it was summer hot with highs at or above 90 and more humidity than is normal for early April. I was on vacation and glad for the summery temperatures [1], but as I sweated under the afternoon sun I did have to ask myself whether summer at Easter is really how I would define my perfect climate.

...temperate San Francisco?

And judging by the many comments I received on my three previous Perfect Climate posts, I’d say there is a strong sentiment regarding this topic. I defined what I considered the perfect climate, but many readers have different preferences (see a sampling of reader comments below).

This is the fourth post in my “Perfect Climate” series. To check out the first three, use the following links: The Perfect Climate – Part 1 The Perfect Climate – Part 2 The Perfect Climate – Part 3

Fortunately, one of the benefits of the climate ranking system I developed is that it can be adjusted for different tastes. I’d like to examine one such adjustment, one that addresses the question I posed at the beginning of this post. But first, a review of my ranking system.

Conroy’s Perfect Climate
Most people have their preferences for what makes a perfect climate, but as I explained in Part 1 I feel that temperature is the key factor and dominates humidity, and other elements like sunshine, wind, and precipitation. When it comes to temperature there are four variables to consider:

• mean annual temperature, the higher the better [2]; 
• the variance between the hottest month and the coldest month, the lower this difference (the less extreme the seasonality) the better [3]; 
• the mean temperature for each month of the year, the more “comfortable” the monthly mean the better (or stated another way: How comfortable is it at any given time of the year?) [4]; and 
• the mean diurnal temperature differences by month (the difference between daily high and low), the lower the better because a comfortable daily mean doesn’t mean much if actual daily temperatures vary greatly [5].

I use historical temperature data [6] for a city and apply it to a formula I developed [7] that yields a climate score [8]. The higher the climate score, the better the climate. I computed the score for nearly 500 places in the United States. The top three climate scores are associated with Hilo, Hawaii, Honolulu, and Key West. The three lowest scores belong to Nome, Fairbanks, and Barrow, Alaska. I doubt that many people would quibble with these results. The ranking of climate scores for the 30 largest U.S. metropolitan areas is provided in the table below. For a full discussion of how I used the four temperature variables to quantify the perfect climate, read The Perfect Climate – Part 1 post, and for commentary on the rankings see The Perfect Climate – Part 2.

Climate Rankings for the 30 Largest Metropolitan Areas
Rank	Metropolitan Area	Climate Score
1	Miami, FL	44.9
2	Tampa, FL	37.8
3	Los Angeles, CA	37.1
4	Orlando, FL	36.4
5	San Diego, CA	36.0
6	Houston, TX	29.5
7	San Francisco, CA	27.9
8	Riverside, CA	25.3
9	San Antonio, TX	23.9
10	Sacramento, CA	22.4
11	Phoenix, AZ	21.0
12	Dallas, TX	18.0
13	Atlanta, GA	16.6
14	Seattle, WA	14.2
15	Portland, OR	13.9
16	Las Vegas, NV	13.0
17	Baltimore, MD	9.9
18	Washington, DC	9.0
19	Philadelphia, PA	5.7
20	New York, NY	4.3
21	Cincinnati, OH	3.8
22	St. Louis, MO	3.6
23	Kansas City, MO	3.3
24	Boston, MA	2.5
25	Chicago, IL	1.3
26	Detroit, MI	0.1
27	Pittsburgh, PA	0.1
28	Cleveland, OH	-0.2
29	Denver, CO	-0.4
30	Minneapolis, MN	-12.6

Honolulu is the number 1 big city in my original rankings

After tweaking the formula, computing the climate scores, and analyzing the rankings, I was pleased. The rankings more or less reflected my view of the perfect climate. In particular, places in the hot and humid South and Southeast ranked high, as did temperate California, and then places in the baking Southwest. The lowest ranking places were (of course) freezing Alaska and the highly variable Northern Great Plains.

After I published these rankings I reviewed where Americans have chosen to live over the last half century and the results seem to validate my thinking. People prefer warm winters to cool summers. People will endure high summer heat to avoid freezing winter cold. See The Perfect Climate – Part 3 for more details on the correlation between climate and American demographic trends.

However, as pleased as I was at these results and despite how Americans seem to have (and continue to) vote with their feet for the climates they choose to live in, I received many critical comments on my system and the rankings, including:

“I see that San Diego rates really high, and having spent a lot of time in "America's Finest City", I can attest that it has an almost ideal climate. I much prefer the dryer conditions there than the sticky humidity in Florida.” – CT, Eugene, OR

“Wow! Having escaped Houston's oppressive humidity and 100º heat even in June for Denver's 300+ sunny days/year, I gotta pick my subjective observations over your methodology for picking a place to live!” – Nowitall, Denver, CO

“Ill have to be honest with you about the Florida climate. I've lived in Florida for about 12 years (in the Tampa area) and the climate is nothing to strive for. The summers are absolutely brutal. April- October you have to deal with temps above 90F with a lot of humidity. It’s not the heat as much as it is humidity. Every summer morning I always walk my dog. In the morning it’s about 86F with usually 90 percent humidity. 5 minutes outside and you’re pouring with sweat.” – Anonymous, Tampa

Extreme Temperatures

by Conroy

Two of the most viewed posts on this blog are the “Perfect Climate” posts from last January (Part 1 here and Part 2 here). The whole point of those posts was to identify the “perfect” climate by reviewing the average – the normal – temperatures (daily mean, diurnal variation, seasonal differences, etc.) for hundreds of locations around the United States. During the extensive research for those writings, as I spent many many hours poring over temperature data, I became curious in the opposite, not the normal, but extreme temperatures.

In particular, I wondered what the high and low temperatures were across the entire country on any given day. How hot does the hottest place get in summer or the coldest in winter (and vice versa)? Surely it would be interesting to know this bit of trivia. It took a little searching, but fortunately, I found this exact information published by the National Weather Service (for populated places). Unfortunately, it’s published one day at a time with only the previous couple of days of national highs and lows listed. Also, for whatever reason, the NWS only publishes this information for the continental U.S., no Alaska or Hawaii (or for that matter, no Puerto Rico, Guam, American Samoa, etc.). Based on the lower 48’s extreme temperatures, Hawaii may occasionally have the nation’s warmest weather, but Alaska would almost certainly claim the coldest temperatures on most days (October to April anyway).

I patiently compiled the daily U.S. high and low temperatures (and the corresponding location) over the last year (January 22, 2011 to January 21, 2012). Some would call this obsessive or silly or strange, to which I can offer no really good rejoinder. But I did it, and crunching the numbers I found some interesting things to note (all temperature values in degrees Fahrenheit):

Extreme Temperature Facts

Bullhead City - likely on a hot day

Highest high.  On back-to-back summer afternoons, August 24 and 25, in Bullhead City, Arizona, the thermometer hit a suffocating 119 degrees. Bullhead City is located in the heart of the Mohave Desert along the Colorado River about 90 miles south of Las Vegas. The 119 degree temperature is actually seven degrees below Bullhead City’s record high of 126 degrees (126!). There were fourteen other days when the national high was at least 115 degrees, and all but one of those recordings was unsurprisingly taken in the desert southwest (Arizona and California).

Let me digress to discuss record high temperatures. The highest recorded temperature in North America, and the second highest ever recorded on Earth, is 134 degrees at Furnace Creek in Death Valley, California on July 10, 1913. That was nearly a century ago, and I have no idea who was reading that temperature, how the thermometer was calibrated, or whether it was even set-up right. Call me a skeptic, but 134 degrees in the shade seems rather high even for a record high temperature. Similarly, the highest ever recorded temperature on Earth – 136 degrees – was recorded in the Sahara at Aziziya, Libya on September 13, 1922. This 90-year-old recording is in dispute. If it is indeed inaccurate, what is the real highest temperature recorded in modern times?

The Perfect Climate - Part 3

by Conroy

To read the first two parts of this climate series, use these links:
The Perfect Climate - Part 1
The Perfect Climate - Part 2

"...[Detroit's] winters are cruel - January temperatures average 24.7 degrees - and Americans do seem to love warm weather. Over the last century, no variable has been a better predictor of urban growth than temperate winters."

     - Edward Glaeser, The Triumph of the City

The cold is one reason people continue to flee Detroit

This excerpt from Glaeser's wonderful new book supports the argument that I have been making in my climate rankings. That is, that the warmer the weather, and especially the warmer the winter, the better.

In Part 1, I presented my climate formula and the ranking of all U.S. metropolitan areas. In Part 2, I provided some commentary on these rankings. I received many comments from readers in support of cold locations that ranked low on my rankings. I even received vehement arguments from residents of Barrow, Alaska and Leadville, Colorado extolling the virtues of these very cold climates. Of course these perspectives are totally valid, but my argument remains that most people prefer warm to cold. My intuition told me that U.S. demographic trends substantiated this assertion, and the expert analysis of Glaeser supports it even further. Still, it's worth testing my intuition and Glaeser's statement with facts.

Here is a list of the ten metropolitan areas that have see the largest net increase in population since 1950 along with their climate score and associated rank among the 30 largest metropolitan areas:

[Note the population changes are approximate because the Census Bureau has changed the definition for metropolitan areas multiple times since 1950.]

(population change in thousands of people / climate score / rank out of top 30 metro areas)
1. Los Angeles, CA - 8,530 / 37.1 / 3
2. New York, NY - 6,190 / 4.3 / 20
3. Dallas, TX - 5,790 / 18.0 / 12
4. Houston, TX - 5,090 / 29.5 / 6
5. Miami, FL - 5,000 / 44.9 / 1
6. Atlanta, GA - 4,830 / 16.6 / 13
7.Chicago, IL - 4,100 / 1.3 / 25
8. Phoenix, AZ - 4,070 / 21.0 / 11
9. Washington, D.C. - 4,040 / 9.0 / 18
10. Riverside, CA - 3,800 / 21.3 / 8

People continue to move to "warm" Dallas and other Texas cities

Seven of the ten cities on this list can be described as "warm" with mild winters. The only three on the list that have cold winters are New York, Chicago, and Washington, D.C. (and Washington occasionally experiences mild winters). It makes sense that New York and Chicago would be on this list because of their size and economic importance. Washington ranks because of the massive growth of the federal government since World War II.

But consider the other seven cities on this list. Only Los Angeles ranked among the ten largest metropolitan areas in 1950. Now five of these cities do with Phoenix and Riverside ranked 12th and 14th, respectively. If current trends continue, these two cities will probably rank 10th and 11th within this decade.

Surely there are more than just climate factors driving the growth of these cities. Dallas, Houston, and Atlanta all have the reputation as business-friendly, job-rich regions. But the correlation of warm temperatures to population growth is compelling.