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Earth Has its Hottest Summer and Hottest August on Record

By: Jeff Masters 4:00 PM GMT on September 17, 2015

August 2015 was Earth's hottest August on record, and the Northern Hemisphere summer period of June-July-August was the hottest summer since record keeping began in 1880, said NOAA's National Centers for Environmental Information (NCEI) on Thursday. NASA rated August 2015 as the 2nd warmest August on record, a scant 0.01°C from tying August 2014's record mark. August 2015's warmth makes the year-to-date period (January - August) the warmest such period on record, according to both NOAA and NASA. NOAA said that August 2015 was the sixth month in 2015 to break its monthly temperature record, joining February, March, May, June, and July. August 2015 tied with January 2007 for the third warmest monthly departure from average of any of the 1628 months since records began in January 1880 (the record warmest departures occurred in February 2015 and March 2015). Over the oceans, August 2015 had the warmest departure from average of any month in the historical record (previous record: July 2015.) A potent El Niño event in the Eastern Pacific that crossed the threshold into the "strong" category in early July continues to intensify, and strong El Niño events release a large amount of heat to the atmosphere, typically boosting global temperatures by at least 0.1°C. This extra bump in temperature, when combined with the long-term warming of the planet due to human-caused emissions of heat-trapping gases like carbon dioxide, makes it extremely likely that 2015 will be Earth's second consecutive warmest year on record. The UK Met Office put out a press release earlier this week predicting that 2016 will continue to see record or near-record levels of global heat, and it is quite possible that Earth will see three consecutive years with record-breaking surface temperatures: 2014, 2015, and 2016.

Figure 1. Departure of temperature from average for August 2015, the warmest August for the globe since record keeping began in 1880. Record warmth was observed across South America and parts of Europe, Asia, and Africa. Record warmth was also over much of the world's oceans, including the waters surrounding Hawaii, where the warm waters are expected to cause a significant coral bleaching episode resulting in a large-scale die-off of coral. Image credit: National Centers for Environmental Information (NCEI) .

Global satellite-measured temperatures in August 2015 for the lowest 8 km of the atmosphere were the 3rd warmest in the 37-year record, according to the University of Alabama Huntsville (UAH). The lowest 8 km of the atmosphere heats up dramatically in response to moderate to strong El Niño events, with a time lag of several months--as occurred during the El Niño events of 1998 and 2010, the only two years that had warmer August temperatures than 2015. Earth's lower atmosphere temperature will likely hit record levels by early 2016.

Two billion-dollar weather disasters in August 2015 in China
Two billion-dollar weather-related disasters hit the Earth last month, both in China, according to the August 2015 Catastrophe Report from insurance broker Aon Benfield: Typhoon Chan-hom ($1.6 billion in damage) and flooding August 20 - 24 that caused $1.2 billion in damage. With fifteen billion-dollar weather disasters through August 2015, Earth is on pace for a below-average number of such disasters, compared to statistics from the past ten years.

Disaster 1. Typhoon Chan-hom made landfall about 80 mi south-southeast of Shanghai, China on August 11, killing 16 people and doing at least $1.5 billion in damage. The typhoon did another $100 million in damage to Guam, Japan, Taiwan, and Korea. In this image, we see people watching huge waves from Chan-hom pounding Wenling, in east China's Zhejiang province, on August 10, 2015. Image credit: STR/AFP/Getty Images.

Disaster 2. Heavy rainfall in China from August 20 - 24 killed 28 people and did $1.2 billion in damage. More than 238,000 residents were evacuated as floods and landslides destroyed 7,770 homes and damaged 35,100. In this picture, we see vehicles stranded on a flooded road in Wuhan, Hubei Province of China, on August 23, 2015, when 160.2 millimeters (6.31") hit the city. This was their heaviest daily rainfall since 1998, according to Changjiang Times. Image credit: ChinaFotoPress/Getty Images.

Most expensive disaster in Dominica's history
August 2015 also saw one nation experience its most expensive disaster in its history: the Caribbean island of Dominica (population 72,000), where Tropical Storm Erika unleashed a catastrophic deluge on August 27 that brought extreme flooding. The storm caused $612.7 million in damage to roads and bridges, $39.5 million in damage to the airport, and an additional $12 million in clean up costs (thanks go to David C. Adams of Thomson Reuters for this info.) Erika's total preliminary price tag of $675 million East Caribbean dollars, which is about $275 million U.S. dollars--not far from Dominica's annual GDP of $500 million. The storm will likely set the island back 20 years in development, Prime Minister Skerrit said. According to EM-DAT, the international disaster database, Dominica's previous most expensive disaster was the $175 million in damage from Hurricane Marilyn of 1995. Erika's death toll of at least 31 makes it the 3rd deadliest disaster in Dominica's history behind the 40 killed in 1979's Hurricane David and the 2,000 people killed in Dominica by The Dominican Republic Hurricane of 1930.

Video 1. Floodwaters rage through a street on Dominica island in the Caribbean on Thursday, August 27, 2015, after Tropical Storm Erika dumped 12+" of rain on the island.

Deadliest weather disaster of August 2015: Asian monsoon floods
The deadliest weather-related disaster of August 2015, according to insurance broker Aon Benfield, was the monsoon flooding during the first week of August that left more than 303 people dead in India, Bangladesh and Pakistan. At least 250,000 homes were damaged or destroyed by floodwaters and landslides in India, and 89,000 homes in Bangladesh.

However, an even deadlier disaster may have been the heat wave and wildfires that beset Central & Southern Europe and the Middle East. At least 109 direct heat deaths occurred in Egypt in August, and hundreds more indirect heat deaths (excess mortality) likely occurred in areas affected by the intense August heat.

Figure 2. A Pakistani army soldier drops a bag of relief food from an army helicopter to flood affected villagers in the Rajanpur district, in Punjab province, on August 6, 2015. A spokesman for Pakistan's National Disaster Management Agency said that 116 people had died and more than 850,000 people had been affected around the country by this year's monsoon floods. Image credit: SS MIRZA/AFP/Getty Images.

Arctic sea ice falls to 4th lowest August extent on record
Arctic sea ice extent during August 2015 was the 4th lowest in the 36-year satellite record, according to the National Snow and Ice Data Center (NSIDC). Sea ice extent likely reached its annual minimum extent on September 11, bottoming out at the 4th lowest extent on record.

Notable global heat and cold marks set for August 2015
Hottest temperature in the Northern Hemisphere: 52.5°C (126.5°F) at Mitribah, Kuwait, August 2
Coldest temperature in the Northern Hemisphere: -42.4°C (-44.3°F) at Geo Summit, Greenland, August 28
Hottest temperature in the Southern Hemisphere: 42.5°C (108.5°F) at Villamontes, Bolivia, August 31
Coldest temperature in the Southern Hemisphere: -82.6°C (-116.7°F) at Concordia, Antarctica, August 27

Major stations that set (not tied) new all-time heat or cold records in August 2015
Charlotte Amalie AP (U.S. Virgin Islands) max. 35.0°C August 1
Nihonmatsu (Japan) max. 38.0°C August 2
Ishikawa  (Japan) max.  37.5°C August 2
Chizu   (Japan) max. 36.9°C August 2
Higashishirakawa (Japan) max. 36.4°C August 3
Osmaniye (Turkey) max. 43.2°C August 3
Baku (Azerbaijan) max. 41.2°C August 4
Salahaddin (Iraq) max. 41.4°C August 4
Nemuro (Japan) max. 33.6°C August 5
Attoko (Japan) max. 34.9  August 5 
Ikeda (Japan) max. 37.1°C August 5
Nukanai (Japan) max. 36.7°C August 5
Kamisatsunai  (Japan) max. 34.6°C August 5
Sarebetsu (Japan) max. 37.1°C August 5
Taiki (Japan) max. 35.8°C August 5
Taneichi (Japan) max. 35.4°C August 5
Wakayanagi (Japan) max. 36.9°C August 5
Senmaya (Japan) max. 36.2°C August 5
Kashimadai (Japan) max. 35.8°C August 5
Esashi (Japan) max. 37.3°C August   5
Yanagawa (Japan) max. 39.7°C August 5
Funahiki (Japan) max. 34.9°C August  5
Ononimachi (Japan) max. 36.0°C August  5
Monte Rosa Obs. (Italy) max. 9.3°C August 5
Mont Blanc Obs. (Italy) max. 6.1°C August 6
Yoneyama (Japan) max. 36.3°C August  6
Shiogama (Japan) max. 35.8  August 6
Otawara  (Japan) max. 36.8  August 6
Ajiro (Japan) max.  36.8°C August 6
Kawamoto (Japan) max. 37.4°C August 6
Oasa (Japan) max. 35.1°C August 6
Chiba (Japan) max. 38.5°C August 7
Genoa (Italy) max. 38.5°C August 7
Albenga (Italy) max. 38.0°C August 7
Capo Mele (Italy) max. 37.0°C August 7
Strasbourg Airport  (France) max. 38.7°C August 7
Mergentheim (Germany) max. 40.2°C August 7
Mannheim (Germany) max. 39.8°C August 7
Lahr (Germany) max. 39.5°C August 7
Frankfurt City (Germany) max. 39.6°C August 7
Berlin Kaniswall (Germany) max. 38.9°C August 7
Ohringen (Germany) max. 38.9°C August 7
Wurzburg (Germany) max. 39.4°C August 7
Gorlitz (Germany) max. 37.9°C August 7
Plauen (Germany) max. 37.8°C August 7
Wasserkuppe (Germany) max. 32.4°C August 7
Usti nad Orlici (Czech Republic) max. 37.4°C August 7
Stara Boleslav (Czech Republic) max. 38.9°C August 7
Paseka (Czech Republic) max. 37.9°C August 7
Dosky (Czech Republic) max. 38.0°C August 7
As (Czech Republic) max. 34.9°C August 7
Harrachov (Czech Republic) max. 33.9°C August 7
Tuhan (Czech Republic) max. 38.6°C August 7
Javornik (Czech Republic) max. 37.5°C August 7
Krasne Udoli (Czech Republic) max. 35.2°C August 7
Rychnov nad Kneznou (Czech Republic) max. 36.8°C August 7
Wroclaw (Poland) max. 38.9  August 8
Prague Karlov (Czech Republic) max. 38.9°C August 8   
Tuhaň (Czech Republic) max. 38.8°C August  8
Pruhonice (Czech Republic) max. 38.7°C August  8
Ceska Lipa (Czech Republic) max. 38.6°C August  8
Javornik (Czech Republic) max. 38.2  August  8
Pribram (Czech Republic) max. 38.1°C August  8
Semcice (Czech Republic) max. 38.1°C August  8
Doksy (Czech Republic) max. 38.0°C August  8
Minsk (Belarus) max. 35.8°C August 8
Kaunas (Lithuania) max. 35.3°C August 8
Bajandaj (Russia) max. 35.8°C August 8
Kurume (Japan) max. 38.5°C August  8
Aso Otohime (Japan) max. 34.6  August 8
Hitoyoshi (Japan) max. 37.8°C August 8
Hong Kong Observatory (Hong Kong,China) max. 36.3°C August 8
Happy Valley (Hong Kong, China) max. 37.9°C August 8, New Territorial record high for Hong Kong
Hong Kong Int. Airport (Hong Kong,China) max. 37.7°C August 9
Trieste Airport (Italy) max. 37.8°C August 9
Brest (Belarus) max. 36.7°C August 9
Wamena (Indonesia) min. 4.5°C August 15
Sisian (Armenia) max. 36.2°C August 16
Vanadzor (Armenia) max. 36.1°C August 16
Ardebil (Iran) max. 40.5°C August 16
Santo Domingo (Dominican Republic) max. 37.2°C August 27
Jerusalen (Colombia) max. 41.0°C August 29

New all-time national and territorial heat records set or tied in 2015
As of September 14, 2015, twelve nations or territories tied or set all-time records for their hottest temperature in recorded history in 2015, and two (Israel and Cyprus) set all-time cold temperature records. For comparison, only two nations or territories set all-time heat records in 2014, and nine did in 2013. The most all-time national heat records held by any year is nineteen in 2010. Most nations do not maintain official databases of extreme temperature records, so the national temperature records reported here are in many cases not official. I use as my source for international weather records researcher Maximiliano Herrera, one of the world's top climatologists, who maintains a comprehensive list of extreme temperature records for every nation in the world on his website. If you reproduce this list of extremes, please cite Maximiliano Herrera as the primary source of the weather records. Wunderground's weather historian Christopher C. Burt maintains a database of these national heat and cold records for 235 nations and territories on wunderground.com's extremes page. Here are the all-time national or territorial heat and cold records set so far in 2015:

Anguilla set its national heat record on September 12, when the mercury hit 33.8°C (92.8°F) at The Valley Airport.
The U.S. Virgin Islands set their national heat record on September 10, when the mercury hit 35.6°C (96°F) at Charlotte Amalie Airport. Note: the unofficial record listed by NOAA for the U.S. Virgin Islands is 99°F at the Charlotte Amalie Airport in 1988, 1994, and 1996. Mr. Herrera has researched the history of temperature measurements in the islands, and found that data taken at this airport was generally reliable after 1998 and before 1972. Between 1972 to 1998, the data was seriously flawed, with minimum temperatures up to 20°F from the real temperature. There is one other reliable station at the St. Croix Airport, with good data back to 1992. The other dozen or so stations in the islands have data of poor quality.
Hong Kong set its national heat record on August 9, when the mercury hit 37.9°C (100.2°F) at Happy Valley.
Germany set a new national heat record of 40.3°C (104.5°F) twice this year: on July 5 and August 7, both at the Kitzingen station in Bavaria.
Vietnam tied its national heat record of 42.7°C (108.9°F) at Con Cuong on May 30.
Palau tied its national heat record of 34.4°C (94.0°F) at Koror Airport on May 14.
Venezuela set a new national heat record of 43.6°C (110.5°F) at Coro on April 29.
Laos tied its national heat record of 42.0°C (107.6°F) at Thakhek on April 20.
Ghana set a new national heat record of 43.3°C (109.9°F) at Navrongo on April 10. This is the third time this year Ghana has tied or set a new all-time heat record.
Cocos Islands (Australian territory) tied their all-time heat record with 32.8°C (91.0°F) on April 8.
Equatorial Guinea set a new national heat record of 35.5°C (95.9°F) at Bata on March 17.
Wallis and Futuna Territory (France) set a new territorial heat record with 35.5°C (95.9°F) on January 19 at Futuna Airport.

Israel set a new national cold record of -14.2°C (6.4°F) at Merom Golan on January 10.
Cyprus set a new national cold record for an inhabited place of -10.7°C (12.7°F) at Prodromos on January 9 (and also a new cold record for an uninhabited place of -12.0°C at the new mountain station of Troodos Square; unofficial readings in the past were as low as -13°C, though).

Special Mentions:
Antarctica set a new heat record for its mainland of 17.5°C (63.5°F) at Esperanza Base on March 24. Previous record: 17.4°C (63.3°F) at Marambio Base, set the previous day. The World Meteorological Organization (WMO) has appointed a committee to study this event and determine if this represents an official record for the continent. Note that this is a record for mainland Antarctica, not a territorial or continental record. The all-time maximum record for the continent and territory of Antarctica is 19.8°C (67.6°F) on January 30, 1982, in Signy Island, South Orkney, an island group located about 450 miles northeast of the tip of the Antarctic Peninsula, the northernmost portion of mainland Antarctica. Geologically, the South Orkney are on the Antarctic plate, and politically, they are part of Antarctica. This record was improperly listed as a territorial record for Antarctica in May's global summary.

Switzerland had its highest reliably measured temperature on record in Geneva on July 7, when the mercury hit 103.5°F (39.7°C). The only higher temperature ever measured in the country was a 106.7°F (41.5°C) reading on August 11, 2003 at Grono. As reported at the Swiss news site swissinfo.ch, this old record was achieved "using an old measurement technique of weather huts, which generally recorded temperatures a few degrees higher than modern instruments." Weather records researcher Maximiliano Herrera agrees that this year's 39.7°C reading in Geneva is the highest reliably measured temperature ever in Switzerland, though the August 11, 2003 temperature at Grono was probably warmer (near 40°C), after correcting for the known problems with the site.

Samoa was originally listed by Mr. Herrera as tying its national heat record with 36.5°C (97.7°F) on January 20 at Asau, but a subsequent review of the record revealed possible issues with the measurement equipment, so this record is dubious.

Kudos also to Mr. Herrera for supplying the data for the "Notable global heat and cold marks set for August 2015" and "Major stations that set (not tied) new all-time heat or cold records in August 2015" sections.

Jeff Masters

Heat Climate Summaries

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.