May 2023 was Earth’s third-warmest May since global record-keeping began in 1850. It was 0.97 degree Celsius (1.75°F) above the 20th-century average, NOAA’s National Centers for Environmental Information reported May 14. NASA also rated May as the third-warmest May on record; the European Copernicus Climate Change Service rated it the second-warmest May, and the Japan Meteorological Agency rated it the warmest May on record.

Map shows global departure of temperature from average in May 2023
Figure 1. Departure of temperature from average for May 2023, the third-warmest May for the globe since record-keeping began in 1850. Parts of the eastern and southern Atlantic, the southern Pacific, the southwestern Indian Ocean, as well as parts of northwestern Canada and several countries in South America, saw record-warm May temperatures. Combined, record-warm temperatures covered just over 6% of the world’s surface in May. No areas experienced record cold. (Image credit: NOAA/NCEI)

Land areas had their eighth-warmest May on record in 2023, with global ocean temperatures the warmest, according to NOAA. This marked the second consecutive month with record-high ocean temperatures.

North America and South America had their warmest May on record; Africa had its eighth-warmest May; Asia had its 16th-warmest May; and Europe had its 20th-warmest May. Oceania had a below-average May temperature.

The year-to-date period of January-May is the fourth-warmest on record. And according to NOAA’s latest Global Annual Temperature Rankings Outlook and the statistical model it uses, there’s a 12.9% chance of 2023 being the warmest year on record and an 89% chance of its being a top-five warmest year. Over the past 10 years, approximately 40% of Earth’s surface area and half the human population have experienced the hottest single day locally in analyses going back to 1950 (see Tweet below).

NOAA said that the contiguous U.S. experienced its 11th-warmest and 29th-driest May in 129 years of record-keeping. Eight northern states had a top-10 warmest May; only South Carolina had a top-10 coldest May.

Canada had its warmest and seventh-driest May since at least 1940, and by one measure, its wildfire season is already the worst since satellite measurements began in 2000 (see Tweet below). The acreage burned so far in 2023 ranks as the fourth-highest for an entire year since 1983, with the usual peak of fire season more than a month away. Fighting Canada’s fires has already cost more than $1 billion Canadian.

NOAA makes it official: El Niño is here

As discussed in our post last week, for the first time in four years, El Niño conditions are in place over the eastern tropical Pacific. NOAA declared the start of the long-expected El Niño event Thursday, June 8, with the issuance of an El Niño Advisory. NOAA gave an 84% chance of at least a moderate El Niño developing by the November-January period — and a 56% chance of a strong El Niño.

NOAA’s and Columbia University’s International Research Institute for Climate and Society ENSO forecast for the peak portion of the Atlantic hurricane season (August-September-October) is a 0% chance of La Niña, a 5% chance of neutral conditions, and a 95% chance of El Niño. El Niño events tend to suppress Atlantic hurricane formation because of an increase in wind shear over the Main Development Region for hurricanes, particularly over the Caribbean. However, with record-warm waters in place over much of the North Atlantic, the season may be more active than usual for an El Niño year.

Arctic sea ice: 13th-lowest May extent on record

Arctic sea ice extent during May 2023 was the 13th-lowest in the 45-year satellite record, according to the National Snow and Ice Data Center. Antarctic sea ice extent in May was the lowest on record, about 18% lower than the 1981-2010 mean and far below any other May (see tweet below).

Southeast Asia heat wave ‘virtually impossible’ without climate change

During May, a phenomenal heat wave in Southeast Asia set all-time national heat records in Laos, Vietnam, and Singapore, plus all-time heat records at 76 stations with a long-term period of record in China, Vietnam, Laos, Thailand, and Myanmar. According to the China Meteorological Administration, a total of 446 national meteorological stations across the country recorded “daily maximum temperature [that has] reached or exceeded the historical extreme values for May.” 

Human-caused climate change made May’s record-breaking humid heat wave in Bangladesh, India, Laos, and Thailand at least 30 times more likely, and was a 1-in-200-year event, that would have been “virtually impossible” without human-caused climate change, according to rapid attribution analysis by an international team of leading climate scientists as part of the World Weather Attribution group. The study also concludes that the high vulnerability in the region, which is one of the world’s heat wave hot spots, amplified the impacts.

Notable global heat and cold marks for May 2023

The information below is courtesy of Maximiliano Herrera. Follow him on Twitter: @extremetemps

– Hottest temperature in the Northern Hemisphere: 49.0°C (120.2°F) at Jacobabad, Pakistan, May 21;
– Coldest temperature in the Northern Hemisphere: -40.8°C (-41.1°F) at Summit, Greenland, May 2;
– Hottest temperature in the Southern Hemisphere: 38.3°C (100.9°F) at Khorixas, Namibia, May 1; and
– Coldest temperature in the Southern Hemisphere: -78.6°C (-109.5°F) at Vostok, Antarctica, May 12.

Major weather stations in May: 77 all-time heat records, no all-time cold records

Among global stations with a record of at least 40 years, 77 set, not just tied, an all-time heat record in May, and no stations set an all-time cold record:

Ceheng (China) max. 41.4°C, May 5;
Longling (China) max. 41.9°C, May 5;
Xilin (China) max. 41.1°C, May 5;
Changjiang (China) max. 41.5°C, May 6;
Lingao (China max. 41.2°C, May 6;
Tianyang (China) max. 40.9°C, May 6;
Hoi Xuan (Vietnam) max. 44.1 °C, May 6; 
Cao Bang (Vietnam) max. 40.6 °C, May 6;
Ha Tinh (Vietnam) max. 41.5 °C, May 6;
Hoa Bin (Vietnam) max. 42.5 °C, May 6;
Sattahip (Thailand) max. 39.6 °C, May 6;
Luang Prabang (Laos) max. 43.5 °C, May 6: New national record high for Laos;
Vientiane (Laos) max. 42.5 °C, May 6;
Samneua (Laos) max. 36.6 °C, May 6;
Tuong Duong (Vietnam) max. 44.2°C, May 7: New national record high for Vietnam;
Udon Thani (Thailand) max. 44.1°C, May 7;
Nong Khai (Thailand) max. 43.7°C, May 7;
Bangkok (Thailand) max. 41.0°C, May 7;
Bhamo (Myanmar) max. 42.5°C, May 8;
Falam (Myanmar) max. 34.0°C, May 8;
Viengsay (Laos) max. 36.6 °C, May 22;
Faya (Chad) max. 48 °C, May 25: New national record high for Chad;
Fengshun (China) max. 39.7 °C, May 30;
Sihui (China) max. 39.2 °C, May 30;
Huili (China) max. 35.2 °C, May 30;
Yunxian (China) max. 39.2 °C, May 30;
Nanjian (China) max. 37.0 °C, May 30;
Yunlong (China) max. 36.0 °C, May 30;
Ximeng (China) max. 35.8 °C, May 30;
Mouding (China) max. 35.5 °C, May 30;
Da Yao (China) max. 34.7°C, May 30;
Fengqing (China) max. 33.8°C, May 30;
Yongsheng (China) max. 32.9°C, May 30;
Baoshan (China) max. 32.7°C, May 30;
Xiangyun (China) max. 32.6°C, May 30;
Yongde (China) max. 32.5°C, May 30;
Anning (China) max. 34.0°C, May 31;
Tonghai (China) max. 33.0°C, May 31;
Eryuan (China) max. 32.3°C, May 31;
Malong (China) max. 31.9°C, May 31;
Gejiu (China) max. 30.6°C, May 31;
Jinyang (China) max. 42.7°C, May 31;
Ningnan (China) max. 42.7°C, May 31;
Mi Yi (China) max. 41.6°C, May 31;
Puge (China) max. 39.7°C, May 31;
Xide (China) max. 37.9°C, May 31;
Mianning (China) max. 36.8°C, May 31;
Zhaojue (China) max. 35.4°C, May 31;
Nandan (China) max. 36.1°C, May 31;
Xinhui (China) max. 38.4°C, May 31;
Maoming (China) max. 38.3°C, May 31;
Yuanmou (China) max. 43.0°C, May 31;
Huaping (China) max. 42.4°C, May 31;
Dongchuan (China) max. 41.8°C, May 31;
Liukuzhen (China) max. 40.6°C, May 31;
Honghe Hani (China) max. 40.4°C, May 31;
Jingdong (China) max. 38.8°C, May 31;
Yongren (China) max. 38.5°C, May 31;
Shuangjiang (China) max. 38.5°C, May 31;
Zhenkang (China) max. 37.4°C, May 31;
Gengma (China) max. 37.0°C, May 31;
Mengzi (China) max. 36.7°C, May 31;
Shiping (China) max. 36.0°C, May 31;
Yimen (China) max. 35.8°C, May 31;
Huaning (China) max. 35.7°C, May 31;
Fumin (China) max. 35.4°C, May 31;
Wuding (China) max. 35.3°C, May 31;
Jiang Chuan (China) max. 34.9°C, May 31;
Yuxi (China) max. 34.9°C, May 31;
Lincang (China) max. 34.9°C, May 31;
Zhaotong (China) max. 34.8°C, May 31;
Chuxiong (China) max. 34.3°C, May 31;
Yongping (China) max. 34.1°C, May 31;
Nanhua (China) max. 34.1°C, May 31;
Qujing (China) max. 34.0°C, May 31;
Hkamti (Myanmar) max. 41.2°C, May 31; and
Myitkyna (Myanmar) max. 41.8°C, May 31.

Five all-time national/territorial heat records set or tied in 2023

As of the end of May, five nations or territories had set or tied an all-time national heat record in 2023:

Thailand: 45.4°C (113.7°F) at Tak Agromet, April 15;
Laos: 42.7°C (108.9°F) at Luang Prabang, April 18; beaten one day later with 42.9°C (109.2°F) at Sayaburi, April 19; beaten again on May 6 and May 7 with 43.5°C (110.3°F) at Luang Prabang;
Vietnam: 44.1°C (111.4°F) at Hoi Xuan, May 6; beaten again with 44.1°C (111.4°F) at Tuong Duong, May 7;
Singapore: 37.0°C (98.6°F) at Ang Mo Kio, May 13 (tie); and
Chad: 48.0°C (118.4°F) at Faya, May 25.

Three all-time national/territorial cold records set or tied in 2023

As of the end of May 2023, three nations or territories had set or tied an all-time national cold record:

Myanmar: -6.0°C (21.2°F) at Hakha, Jan. 17 (tied);
China: -53.0°C (-63.4°F) at Jintao, Jan. 22; and
Cyprus: -12.8°C (8°F) at Trodos Mt. Station, Feb. 8 (tied).

Forty additional monthly national/territorial heat records and three additional monthly cold records beaten or tied

In addition to the five all-time heat records listed above (plus one, for the records set in two different months in Laos), 40 additional monthly all-time heat records have been set in 2023, for a total of 46 all-time monthly heat records:

– Jan. (13): Czech Republic, Liechtenstein, Netherlands, Denmark, Poland, Belarus, Lithuania, Latvia, Romania, Moldova, Ukraine, Cyprus, Nigeria
– Feb. (4): Chile, Taiwan, Pakistan, Cyprus
– March (3): Botswana, Vietnam, Taiwan
– April (11): Cabo Verde, Botswana, Turkmenistan, Mauritius, Antigua and Barbuda, Spain, Morocco, Portugal, Andorra, Saba, St. Barthelemy
May (9): Mauritius, Solomon Islands, Botswana, Cambodia, Cocos Islands, Panama, Saba, Maldives, French Guiana

In addition to the three all-time cold records listed above, three nations or territories have set a monthly all-time cold record in 2023, for a total of six monthly cold records:

– Feb. (1): Montenegro
– March (2): St. Eustatius, Martinique

Hemispherical and continental temperature records in 2023

– Lowest temperature reliably recorded in January in the Southern Hemisphere: -51.2°C (-60.2°F) at Concordia, Antarctica, Jan. 31; and

– Highest temperature ever recorded in April in Europe: 38.8°C (101.8°F) at Cordoba, Spain, April 27.

Bob Henson contributed to this post.

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Jeff Masters, Ph.D., worked as a hurricane scientist with the NOAA Hurricane Hunters from 1986-1990. After a near-fatal flight into category 5 Hurricane Hugo, he left the Hurricane Hunters to pursue a...