Weather Extremes

Unprecedented snow melt and heat in the European Alps

By: weatherhistorian, 8:16 PM GMT on August 25, 2012

Unprecedented snow melt and heat in the European Alps

The recent heat wave in Europe has especially been anomalous at higher altitudes resulting in some of the highest Alpine peaks in Europe being snow-free for the first time on record including the iconic peak Matterhorn.

Early snow melt and record temps at mountain-top stations in the Alps

On August 19th the temperature at Jungfraujoch, Switzerland (the highest railway station in Europe) reached 12.8°C (55.0°F) the warmest temperature ever measured at this site where records began in 1937. This observatory is located at an elevation of 3580m (11,745’) just above the famous railway station.

The Jungfraujoch Observatory of Switzerland is located at an elevation of 3580m (11,745’) and recorded its warmest temperature on record on August 19th this summer with a 12.8°C (55.0°F) reading. Photographer unknown (from Swiss tourism site). Please note that this photograph, and the others following, are archive images of these Alpine sites and do not represent the current situation.

The significance of this is that this site has been studied by European climatologists for 75 years and is considered a 'bell-weather' location because of its long POR and isolation from surrounding possible human-induced influence.

The Jungfraujoch Observatory has the longest (since 1937) temperature time series of any high-altitude (3000m+) weather station in Europe. Graphic and caption from Meteo Swiss.

Another site on the border of Switzerland and Italy near the summit of Mt. Rosa (2nd highest mountain in the Alps after Mt. Blanc) named Capanna Regina Margherita (also known as Mt. Signalkuppe) and located at an elevation of 4554m (14,940’) registered a record temperature of 8.3°C (47.0°F) on August 20th. This surpassed its previous record high of 7.2°C (45.0°F) although records have only been kept here for about 15 years. The minimum temperature at the site that day was -0.1°C (31.8°F), also a record. This is the highest weather station in Europe. The Plateau Rosa near here is snow-free for the first time on record.

The amazing Capanna Regina Margherita is the highest Alpine hostel in Europe at 4554m (14,940’). Weather records here go back to about 2000. On August 20, it measured its warmest temperature on record with a reading of 8.3°C (47°F). Photo from Italian Alpine club web site.

Aguille du Midi, a mountain in the Mt. Blanc massif in the French Alps, with an elevation of 3842m (12,605’) registered a high of 13.4°C (56.1°F) and low of 4.7°C (40.5°F) on August 19th, both records for the site since it was built in 1955. The peak is accessible by a cable car from the ski resort of Chamonix, France. Chamonix (elevation 1035m/3,396’) also recorded its all-time record warmest temperature on August 20th with a 34.4°C (93.9°F) reading. For the first time on record the peak of Aguille du Midi is now snow-free.

Another one of Europe’s spectacular high mountain observatories is just below the peak of Aguille du Midi above the French ski resort town of Chamonix. Both locations registered their warmest temperatures on record last week. Photographer unknown (from Chamonix tourist promotion site).

For the first time in memory many of the highest Alpine peaks, including the iconic Matterhorn, have lost their entire snow cover (aside from glaciers). Sonnblick Observatory in Austria (located at 3030 m/9,940’) had its earliest snow melt on record this summer when the last of the winter snow disappeared by July 31st. The previous earliest snow melt (since records began here in 1886) was August 12th, 2003, the year of the famous European heat wave.

Alpine Glacier Melt

It has been widely recognized (and researched) that most of Europe’s Alpine glaciers have been in retreat for the past 60 years or so. How much of this is due to solar radiation and how much to Global Climate Change remains a center of debate although it would seem that the two are related. An article in Geophysical Research Letters (Vol. 36, 2009) by M. Huss et al studied a 94-year time series of annual glacier melt at four high elevation sites in the Alps and found that the first massive melt off occurred in the late 1940s when “global shortwave radiation over the summer months was 8% above the long-term average and significantly higher than today”. Dimming of solar radiation from the 1950s until the 1980s reduced glacial melt rates. In the 1990s to the current time solar radiation has increased again but this time (since 2000) has also been accompanied by warmer summertime surface temperatures. Thus the glacial melt rates have exponentially increased in the past decade.

A graphic illustrating the Alpine glacier loss at 10 sites in Switzerland between 1980 and 2003. World Glacier Monitoring Service, Zurich.

NASA released this statement at the annual AGU (American Geophysical Union) meeting in San Francisco last December (2011):

“Dec. 12, 2011: A new glacier inventory of the French Alps produced by Marie Gardent and colleagues at the University of Savoie has found that 100 square kilometers of glacier area has been lost between the early 1970s and today—a 26 percent loss. Using Landsat data together with historical aerial photography and maps, Gardent was able to evaluate and compare historic and contemporary glacier surface area.”

The BBC science correspondent, Jonathan Amos, summarized the AGU findings in this article he posted from the conference;

”Glaciers in the French Alps have lost a quarter of their area in the past 40 years, according to new research.

In the late 1960s/early 1970s, the ice fields slipping down Mont Blanc and the surrounding mountains of the European range covered some 375 sq km.

By the late 2000s, this area had fallen to about 275 sq km. The research has been presented at the American Geophysical Union (AGU) Fall Meeting, the world's largest annual gathering of Earth scientists.

It mirrors some findings of retreat occurring in other sectors of the Alps which sit across the borders of several nations, but predominantly Switzerland, Austria, Slovenia, Germany, France, and Italy.

The new French Alps glaciers inventory was produced by Marie Gardent, from the University of Savoie, and colleagues.

It assessed the roughly 600 glaciers in broad areas incorporating the Ecrins, Belledonne, Vanoise, Ubaye and Grande Rousse Arves massifs, as well as the famous Mont Blanc Massif in the north.

The team drew upon map archives, past satellite imagery and aerial photographs. Manual inspection was used to check the automatic delineation methods employed in the pictures was correct.

"We use manual delineation to verify the satellite data because there can be a problem with debris cover on a glacier," explained Ms Gardent.

Automatic delineation from satellite data will sometimes say there is no glacier when in fact we know there is one there. Also, deep shadows can hide the glacier margins."

A great deal of effort is now going into monitoring the status of Alpine glaciers.

The only existing glacial inventory from the French Alps was published four decades ago within the context of the World Glacier Inventory. It found the overall area of ice to be about 375 sq km.

By 1985-86, in spite of a short advancing period in the late 70s/early 80s, glacial coverage had decreased to a value close to 340 sq km, the new survey shows.

Since then, the withdrawal has accelerated, with the area being reduced to about 275 sq km in the late 2000s.

This represents an average loss of some 26% over the last 40 years. The retreat is not uniform across the French Alps, however. The greatest losses have been seen in the southern sectors. In the Belledonne Massif, for example, glaciers have almost completely disappeared; and in the Ecrins Massif, glacial retreat is more than three times stronger than in the Mont Blanc Massif.

“The glacier retreat is less important in the northern Alps than in the southern Alps," Ms Gardent emphasized, "We think this is because of the lower elevation of the mountains in the south, but also because of climatic conditions which are different. There is more precipitation in the north and there is also more cloud."

The northern region includes the biggest French glacier of all - La Mer de Glace, which falls over a 1,000m in altitude down Mont Blanc itself. Its area today is just over 30 sq km, a shade smaller than the 31.5 sq km in the late 1960s/early 1970s.

Efforts to assess and monitor glacier health are going on across the Alpine region.

At this very meeting three years ago, Swiss researchers reported that glaciers on their part of the European range were also losing mass at an accelerating rate.

The Pasterze Glacier in Austria as photographed in 1875 (top) and then again in 2004 (bottom). Bottom photo by Gary Braasch.


This summer has, no doubt, also had a dramatic affect on the on-going Alpine glacial retreat given the record warm temperatures measured at the highest elevations of the mountains.

KUDOS: Maximiliano Herrera for latest temperature data at high-altitude Alpine weather stations.


Strong Alpine glacier melt in the 1940s due to enhanced solar Radiation, Geophysical Research Letters (Vol. 36, Dec. 3, 2009) by M. Huss, M. Funk, and A. Ohmura.

French Alpine glaciers in retreat By Jonathan Amos Science correspondent, BBC News, December 6, 2011

“Potential climatic transitions with profound impact on Europe. Review of the current state of six ‘tipping elements of the climate system’ by Anders Levermann, Jonathan L. Bamber, Sybren Drijfhout, Andrey Ganopolski, Winfried Haeberli, Neil R. P. Harris, Matthias Huss, Kirstin Krüger, Timothy M. Lenton and Ronald W. Lindsay, et al. Climate Change (journal) Vol. 110, No. 3-4 (2012)

Christopher C. Burt
Weather Historian

Heat Climate Change

Updated: 6:27 AM GMT on August 27, 2012


U.S. Summer heat wave packs bag and heads to Europe for holiday UPDATED 8/20

By: weatherhistorian, 8:14 PM GMT on August 18, 2012

U.S. Summer heat wave packs bag and heads to Europe for holiday: UPDATED 8/20: A new national all-time heat record has been broken for the Czech Republic today (August 20)

After touring the U.S. for two months (since mid-June) the great heat waves of the summer of 2012 have apparently decamped for Europe after a recent visit to the interior of the U.S. Southwest. Record-breaking heat is now forecast to impact the Iberian Peninsula and other portions of Western Europe in the coming week. In fact, a short but very intense heat wave has already afflicted portions of the continent earlier this month.UPDATE for August 20th at end of article.

European Heat Wave of August 6-11

A brief period of intense heat, caused by a southwesterly flow of air from the Sahara Desert, baked a swath of Europe from Spain to the Ukraine on August 6-11.


The Madrid Royal Observatory in Retiro Park recorded its hottest temperature on record with a 40.6°C (105.1°F) reading on August 10th. Records here go back to 1860 (the Madrid Airport location has measured hotter temperatures before with 42.2°C/108°F in August 2003). Elsewhere in Spain all-time records on August 10 and 11 were achieved at:

Cordoba with 46.3°C/115.3°F (downtown location)

Alcoi with 44.1°C/111.4°F

Toledo with 43.1°C/109.6°F

Vitoria (Basque region) with 42.4°C/108.3°F

Pamplona with 41.4°C/106.5°F

Salamanca with 40.9°C/105.6°F

The hottest location of all in Spain was Mengibar, Jaen Province with 47.1°C (116.8°F), a location about 55 miles east of Cordoba). This was just 0.1°C (about 0.2°F) short of the possible Spanish national record of 47.2°C (117.0°F) set at Murcia on July 4, 1994. However, the Spanish heat record is open to debate. A possibly reliable figure of 50°C/122°F was reported from Berja on July 18, 1978. Many sources also claim that Seville also reached 50°C/122° on August 4, 1881. During the recent event Seville recorded 45.9°C/114.6°F.

A NCEP map of temperatures at the 2 meter (6 feet) above surface elevation in degrees Fahrenheit for August 11 during the peak of the heat wave in Spain. Map from WeatherBELL models.


Rome’s Ciampino Airport reached 39.4°C (102.9°F) on August 7th, short of the Rome record of 40.6°C (105.1°F) set in August 1956 and August 1981. Libertinia was the country’s hot spot with 45.4°C (113.7°F) on August 6th (and well short of the Italian national record of 48.5°C (119.3°F) set at Catenanuova, Sicily on August 10, 1999.


Kiev hit 37.6°C (99.7°F), short of their all-time record of 39.4°C (102.9°F). The highest reading observed in the country was 40.4°C (104.7°F) at Mohyliv-Podil’s Kyi. The Ukrainian national record of 42.0°C (107.6°F) at Lukhansk on August 12, 2010 still stands.

Other national maximum temperatures include the following:


43.5°C (110.3°F) at Rousse on August 7. National record is 45.2°C (113.4°F) at Sadovo on August 5, 1916.


42.5°C (108.5°F) at Bacau on August 7. National record is 44.5°C (112.1°F) at Ion Sion on August 10, 1951.


42.8°C (109.0°F) at Podgorica on August 7th. National record is 44.8°C (112.6°F) at Podorica on August 24, 2007.


39.2°C (102.6°F) at Kisinev on August 7. National record is 42.0°C (107.6°F) at Slobozia on July 21, 2007.


42.0°C (107.6°F) at Gjirokastra on August 8. National record is 43.9°C (111.0°F) at Kucove on July 18, 1973.


41.8°C (107.2°F) at Mostar on August 7. National record is 43.1°C (109.6°F) at Mostar on August 24, 2007.


40.8°C (105.4°F) at Gradiste on August 7. National record is 42.8°C (109.0°F) at Ploce on August 5, 1981.


36.7°C (98.1°F) at Zamosc on August 6 and 7 was an all-time record for this site. National record is 40.2°C (104.4°F) at Proszkow on July 29, 1921. Warsaw reached 34.6°C (94.3°F) on August 6, short of their all-time record of 36.4°C (97.5°F).

Heat Returns to Western Europe: August 17-?

Forecast model for 850 hPa temperatures valid or Sunday August 19th.

Another surge of excessively warm air has begun to impact much of southern and Western Europe as I write this. On Friday, August 17th, temperatures in Spain topped out at 43.1°C (109.6°F) at Arroyo del Ojanco, Jaen Province and Madrid (Airport location) reached 38.6°C (101.5°F). Madrid again topped 100°F on Saturday, August 18th with a 38.2°C (100.6°F) reading.

The beaches of Spain and France are overwhelmed with people seeking relief from the intense heat. Still from IBT news video.

The core of the heat now seems to be settling over France where Paris (Orly Airport) topped 100°F on August 18th (38.2°C/100.8°F). This has been the city’s hottest day since the heat wave of 2003 when a reading of 102°F was recorded (the all-time record for Paris is 40.4°C/104.7°F set in 1949). The warmest temperature reported in France on August 18th was 42.3°C (108.1°F) at Montgivray. The official national all-time heat record for France appears to be 42.7°C (108.9°F) at Le Luc-en-Provence on July 7, 1982, however temperatures as high as 44.1°C (111.4°F) were recorded during the great 2003 heat wave on August 12th at St. Christol les Ales.

In Belgium it was 36.5°C (97.7°F) at Kleine Brogel, 35.5°C (95.9°F) at Antwerp (just short of their all-time record of 36.1°C/97.0°F), and 34.5°C (94.1°F) in Brussels. Belgium’s all-time national heat record is 38.8°C (101.8°F) set at Uccle on June 27, 1947.

UPDATE: Sunday, August 19th, did not produce quite as extreme temperatures as Saturday although the heat was worse in some locations, especially in the higher altitudes of the Alps such as at the famous ski resort of Chamonix, France where an all-time record of 34.4°C (94.3°F) was achieved. Madrid failed to reach 100°F (38°C) on Sunday but it endured its hottest minimum temp on record when the low was just 25.8°C (78.4°F). In Andorra a temperature of 37.9°C (100.2°F) was recorded at Roc St. Pere, just 0.6°C short of the Andorran national record of 38.5°C (101.3°F) measured at Andorra La Vella on July 16, 2005. On Monday, August 20, the core of the heat seems to be over Germany (where temperatures up to 39°C/102°F have occurred) and the Czech Republic (where Prague has smashed its all-time record with 39.6°C/103.3°F today--old record was 37.8°C/100.0°F). Both countries (and others) are setting many all-time heat records. I will do an update on August 21st (Tuesday) to review these records.

BREAKING NEWS: A new national all-time heat record has been broken for the Czech Republic today (August 20) with a reading of 40.4°C (104.7°F) at Dobrichovice. This just edges out the former record of 40.2°C (104.4°F) from Uhrineves set on July 27, 1983.

KUDOS: Thanks to Maximiliano Herrera for much of the temperature data reported above.

Christopher C. Burt
Weather Historian


Updated: 4:11 AM GMT on August 21, 2012


July 2012 Global Weather Extremes Summary

By: weatherhistorian, 7:46 PM GMT on August 10, 2012

July 2012 Global Weather Extremes Summary

July 2012 featured many notable extreme weather events from around the world. It was the warmest single month on record for the continental U.S., beating out the infamous July of 1936 by a slim margin. Record warmth occurred on the summit of Greenland’s ice cap and a possible new Asian heat record of 53.6°C (128.5°F) was set in Kuwait. Deadly floods devastated portions of Russia, China, Japan, and North Korea. The most powerful typhoon since 1999 struck Macao and Hong Kong.

Below is a summary some of the month’s highlights.


Persistent heat across much of the continental U.S. resulted in July 2012 being the warmest single month on record since official records began in 1895 according to the NCDC with an average nation-wide temperature of 77.6°F just beating July 1936 (77.4°F), the previous hottest month on record. The beginning of the month saw all-time heat records fall in some southeastern cities like 107°F (41.7°C) in Greenville, South Carolina and 105°F (40.6°C) in Knoxville, Tennessee. An unofficial reading of 112°F (44.4°C), a possible state record, was apparently measured somewhere in Georgia but details on this figure are sketchy. By the 4th of July the heat became centered over the upper Midwest and all-time heat records were broken or tied at Lansing, Michigan with 103°F (39.4°C) and Muskegon, Michigan with 99°F (37.2°C) (both records measured on July 6th). Chicago endured three consecutive days above 100°F (38°C) from July 4-6, tying the modern record for such. For more details on the July heat wave see my previous blog on this subject.

The July 2012 temperature and precipitation rankings by state. NCDC graphics.

An interesting side note to the months heat was the minimum temperature of 107°F (41.7°C) measured on July 12th in Death Valley, California. This is most likely the hottest night ever reliably recorded in the U.S. and ties a similar figure measured just last June in Oman for the world record maximum-minimum.

Colorado’s worst wildfire in history was finally contained early in the month after destroying 300 homes and killing two near Colorado Springs.

Drought conditions intensified across much of the country during July, expanding to cover 67% of the country by month’s end, the greatest extent since the Dust Bowl era of the 1930s.

A spectacular photograph of an intense dust storm that enveloped Phoenix, Arizona on July 5th. Photo by Mike Chandler posted on

The Canadian Arctic and Greenland recorded some remarkable warmth during July as well. Alert, Nunavut, Canada at a latitude above 82°N reached 19.6°C (67.3°F) on July 18th. This was just shy of their all-time record high of 20.0°C (68.0°F) set on July 8th, 1956. In Greenland the Summit station at 10,500’ (3300m) on top of the ice cap hit 3.6°C (38.5°F) on July 16th. The first time on record the temperature has risen above freezing. Just 12 days earlier the temperature at Summit was -30.4°C (-22.7°F) on July 4th, this was coldest temperature recorded in the northern hemisphere during the month. Also, for the first time, almost (97%) of the entire Greenland ice sheet showed signs of melting.


The warmest temperature measured in the southern hemisphere during this past July was 39.0°C (102.2°F) at Floriano, Brazil on July 13th.


In the U.K. a cool, wet, and dreary month of July turned warmer, drier, and sunnier just in time for the start of the Olympics in the latter third of the month. It was, however, the coolest July since 2000. The warmest temperature measured was 30.7°C (87.3°F) at St. James Park in London on July 25th and the coldest figure was 0.0°C (32°F) at Resallach, Scotland on July 2nd. Heaviest 24-hour rainfall total was 74.9mm (2.95”) at Slapton, Devon on July 6-7. Dublin, Ireland enjoyed its warmest night in modern records on July 22-23 when the temperature fell to just 17.7°C (63.9°F) besting the previous high-min of 17.6°C (63.7°F) set in June 2005. However, old records from Dublin indicate a minimum of 18.7°C (65.7°F) was measured in July 1881.

Elsewhere in Europe a rare tornado ripped through the northern Polish town of Sztum on July 16th killing one and injuring 10 others.

An intense tornado rips through Sztum, Poland on July 16th. Photographer unidentified.

In Spain hot, dry, and windy weather fanned a wildfire in Portbou near the French border on July 22nd. Two people perished after jumping off a cliff to escape the flames.

One of the world’s deadliest weather disasters during July was the flash flood that struck the Krasnodar region (near the Black Sea) of Russia on July 7-8. Some 300 mm (11.8”) of rain fell in 24 hours near Yalta and the ensuing floods resulted in the deaths of at least 175 people. For more details on this historic flood see Jeff Master’s blog on the event he posted last month.


Marrakech, Morocco recorded the hottest temperature ever reliably measured in that country on July 17th with a 49.6°C (121.3°F) reading. A temperature from Agadir of 51.8°C (125.2°F) on August 17, 1940 has been reported but is suspicious since it exceeded by about 10°F any other reading from nearby locations.

Flooding in the central Nigerian city of Jos killed at least 35 people on July 22-23.


A possible all-time continental heat record for Asia was set on July 31st at Sulaibya, Kuwait when the temperature peaked at 53.6°C (128.5°F). If verified, this would surpass the 53.5°C (128.3°F) recorded at Moen Do-Jaro, Pakistan in May 2010. This was the hottest temperature measured in the world last month (Death Valley made it up to 128°F/53.3°C on July 11th).

Ankara, the capital of Turkey, recorded its all-time hottest temperature on record with a 41.0°C (105.8°F) reading on July 26th (previous record was 40.8°C/105.4°F).

Southern and Eastern Asia suffered through both droughts and floods during the month. In India floods in the Himalayan foothill state of Uttarakhand killed 26 in spite of the fact that the monsoons have by and large failed this year across much of the country. A huge blackout on July 30-Aug. 1 was in part responsible by the grid being overloaded by farmers pumping water to irrigate their crops in drought-stricken regions.

Beijing, China endured its heaviest 24-hour rainfall on record July 20-21 when about 150 mm (6”) of rain fell. Up to 467 mm (18.4”) was reported from suburban Fangshan, 4” of this in just one hour. The resulting floods killed at least 77 people and shut the metropolitan area down for two days.

The Forbidden City’s Tiananmen Square lies submerged under flood waters following the deluge of July 22nd. Xinhua News Agency.

After months of drought, torrential rains slammed the Korean Peninsula during July resulting in devastating floods in North Korea. State media reported at least 175 deaths and the near-complete destruction of its grain crops. Up to 210,000 people have been displaced by the flooding.

Flooding in southwestern Japan left 28 dead following 100 mm (4”) of rain in one hour near Yame. Over 50,000 were ordered to evacuate the area.

The strongest typhoon since 1999 to hit Hong Kong and Macao, Typhoon Vicente, roared ashore on July 22-23 with wind gusts up to 87 mph. The storm unexpectedly intensified from a tropical storm to a Category 3 typhoon in just 12 hours prior to making landfall. Fortunately, there were few deaths reported and 110 injuries as a result of the storm.

A satellite image of Typhoon Vicente just prior to making landfall south of Macao on July 23rd. University of Wisconsin-Madison, Cooperative Institute for Meteorological Satellite Studies.

Typhoon Saola killed 24 and displaced 180,000 in the northern Philippines in late July. The rainfall from the storm began the historic flooding that engulfed Manila in early August.


It was the driest July on record for extreme southwestern Australia including Perth which recorded just 34.6mm (1.36”) of precipitation (previous record was 61.5mm/2.42” in July 1876). For a large portion of central Australia it was the coolest July on record so far as minimum average temperatures were concerned.

The top map shows Australian Rainfall Deciles for July and the bottom map Minimum Temperature deciles for the month. Courtesy of the Australian Bureau of Meteorology.

The warmest temperature in Australia during July was 36.4°C (97.5°F) at Ngukurr, Northern Territory on July 13th and coldest -3.9°C (25.0°F) at Thredbo Top Station, New South Wales on July 6th. The greatest calendar day rainfall was 180.4mm (7.10”) at Daradgee, Queensland on July 10th.


The warmest temperature recorded in New Zealand during the month was 22.6°C (72.7°F) at Rangiora, North Island on July 15th and coldest reading -11.3°C (11.7°F) at Ranfurly, South Island on July 2nd. The greatest calendar rainfall was 336mm (13.23”) at North Egmont, North Island on July 15th.


The coldest temperature in the southern hemisphere and the world during July was -81.1°C (-114.0°F) recorded at Vostok on July 22nd.

KUDOS Thanks to Maximiliano Herrera for global temperature extremes data, Stephen Burt for the U.K. extremes, and Jeremy Budd and NIWA for New Zealand weather extremes.

Christopher C. Burt
Weather Historian

Extreme Weather

Updated: 4:53 AM GMT on August 11, 2012


Recap of record-breaking heat this past July in the U.S. + Asian heat record?

By: weatherhistorian, 8:52 PM GMT on August 02, 2012

Recap of record-breaking heat this past July in the U.S. Possible new heat record for Asia observed

Although the final ranking of this past July will not be released by the NCDC until around August 7th, it would appear that the month will almost certainly rank in the top five warmest July’s on record since official records began in 1895 (and perhaps even in the top three). Here is a summary of some of the more notable records set so far this summer. In addition, I have included a brief message concerning a potential new heat record for the continent of Asia.

Although this map is specifically for July 5th, it represents the overall pattern that most of the country has been stuck with for almost the entire month of July 2012.

Warmest Single Month on Record (any month)

Preliminary data from the NCDC reports that 4,313 record daily highs, 293 monthly record highs, and 171 all-time record highs were observed this past July (among the approximately 5,500 various official weather sites across the nation). Many of these sites, however, have limited periods of record that do not extend back to the 1930s when the country’s greatest heat waves occurred.

The WU extremes U.S. database follows 298 significant sites in the country, all of which have long periods of record (almost all back to the 19th century) and represent a mosaic of evenly spaced geographic locations representing all the climate zones in the country. About 90% of the country’s population resides within a 50-mile radius of one of these sites. From this list the following cities recorded their single-warmest month on record:

The following cities from the WU extremes database have broken or tied their all-time absolute maximum temperatures on record (including this past June):

Comparing this July to July of 2011

Perhaps what is truly astonishing is that this July (2012) piggybacks upon the equally torrid summer (and July) of 2011. Although, back-to-back record-breaking hot summers are not unheard of (summers in the 1930s and 1950s come to mind) it is nevertheless disconcerting.

Here is a comparison of extremes reached in July 2012 versus July 2011. Also, to put this in context, is a comparison to July of 1936, still almost certainly the hottest July (and single month) in U.S. records. Again this list includes only the 298 cities in the WU database:

This table shows the number of cities (out of 298 in all) that recorded their respective single-warmest month on record and absolute maximum temperature on record for the June-July month timeframes in 2012, 2011, and 1936.

Honorable Mentions

Other major cities came VERY close to breaking their all-time warmest single month on record including Washington, D.C. (National Airport) with a July average of 84.0° just shy of the record 84.5° set last July (2011). The Dulles Airport location was also close with 80.6° vs. 81.0° in July 2011. Raleigh, North Carolina averaged 83.5°, shy of their record 84.1° set in August 2007. Chicago, Illinois official site at O’Hare Airport registered an average of 81.1° just short of the 81.3° record set in July 1995. However, the Chicago Midway Airport location, which is more representative of the city itself and also has a much longer period of record (POR) than O’Hare, smashed its all-time warmest month record with an average of 82.6° versus 81.3° in July 1955. Louisville, Kentucky experienced its warmest ever July with an average of 84.5°, but fell short of its single-hottest-month record of 85.0° set in August 2007. Madison, Wisconsin (home of my alma matter!) has just endured its 2nd hottest month on record with a 79.4° average, just short of the record 79.8° set way back in July 1901.

Of course, this is just a short list of the many amazing ‘heat feats’ this past July. I should also mention a couple of the many endurance records that have been set:

Fort Wayne, Indiana: 22 consecutive days above 90° ending on July 18 (old record was 14).

St. Louis, Missouri: 11 days above 105° (old record was 10 in 1934). Also, St. Louis tied its warmest night on record with a low of 86° on July 25th (also occurred on July 24, 1901).

New Asian Heat Record Set?

On a similar topic but different continent, I have late word in from temperature detective Maximiliano Herrera that on July 31st a temperature of 53.6°C (128.5°F) was measured at Sulaibya (Sulaibiya), Kuwait. This location is on the outskirts of Kuwait city and is a water treatment facility.

A Google map image of the location in Kuwait of Sulaibya. Google Earth image.

Although the Kuwaiti meteorological office must make a final determination towards the records validity, a local expert, Dr. Juergen Herrmann (Team Leader Meteorology Specialists, Stanley Consultants, Int’l based in Kuwait) has the following comments in response to a request from Max for additional details:

“We are aware of the new record temperatures. There is no reason why these should not be considered records. Everything is technically OK at the station. You may have detected that the same day we had quiet an amount of other stations in the "vicinity" also have high to record temperatures.

The microclimate at this agro-station is surrounded by high sand dunes and thus has very low wind speeds at 2m height [which] results in a local heat island. Therefore I would not consider this temperature representative for an area bigger than 0.5x0.5km. The next station to Sulaibiya which gives a proper picture for the surrounding area is Jahra - 40586 - and had maximum temperature at the same day of 51.8 deg C. To my best guess this verifies both stations are working properly. Especially as a number of other stations also had really high temperatures that day due to generally low wind speeds with nearly no dust reducing the incoming solar radiation.”

If verified, this would surpass the 53.5°C (128.3°F) measured at Moen Jo-Daro, Pakistan on May 26, 2010. The reading of 54°C (129.2°F) from Tirat Tsvi, Israel on June 22, 1942 remains under suspicion. The Israeli Met. Office pursued an investigation of the record this past year (prompted by an enquiry from the WMO and myself) and concluded it was valid. However, they have refused to make public the details leading to their conclusions, so until they do so the record remains suspect.

KUDOS: Maximiliano Herrera for uncovering yet another possible world record temperature.

Christopher C. Burt
Weather Historian

Temperature Heat

Updated: 11:53 PM GMT on August 02, 2012


Weather Extremes

About weatherhistorian

Christopher C. Burt is the author of 'Extreme Weather; A Guide and Record Book'. He studied meteorology at the Univ. of Wisconsin-Madison.