Jeff Masters Weather Blog

Earth’s hottest month on record » Yale Climate Connections

July 2023 obliterated the record for hottest month in Earth’s history, spiking to a remarkable 1.12 degrees Celsius (2.02°F) above the 20th-century average, NOAA’s National Centers for Environmental Information reported August 14. NASA, Berkeley Earth, and the Japan Meteorological Agency also rated it the warmest month on record in their August 14 reports, as did the European Copernicus Climate Change Service, a few days earlier. Global temperature analyses extend back to 1850 in the NOAA database.

According to Berkeley Earth (see Tweet below), about two-thirds of the July 2023 warmth can be attributed to long-term, human-caused global warming, one-sixth from an intensifying El Niño event, and the remaining one-sixth from such minor contributors as the 2022 Hunga Tonga-Hunga Haʻapai eruption, a reduction in sulfur pollution from recently enacted global shipping emission regulations, and the solar cycle.

Departure of temperature from average since 1880 according to NASA.
Figure 1. Departure of temperature from average since 1880 according to NASA. July 2023 was by far the hottest month in Earth’s recorded history. According to NOAA, “Climatologically, July is the warmest month of the year. As the warmest July on record, July 2023 was more likely than not the warmest month on record for the globe since 1850.”

A record-breaking record-breaker

In the NOAA database, July was 0.20°C (0.36°F) warmer than the previous July record from 2021. In the NASA global temperature database, July’s record margin (topping July 2019) was even larger: 0.24°C (0.50°F). According to NASA, July 2023 was 1.18 degree Celsius (2.12°F) above the average for the 1951-1980 period. This exceeds the former hottest-month record from July 2019 by a remarkable 0.24 degree Celsius (0.43°F). These are huge margins to beat a monthly record by. NASA’s previous largest margin between first and second place for one of the 12 record-warm months is just 0.16 degree Celsius, separating first-place March 2016 from second-place March 2023. NASA rates the margin of error of its annual temperature measurement at 0.05 degree Celsius (.09°F). In the NOAA database, the record first-to-second place margin in the NOAA database is 0.14°C, for both June and February. Thus July 2023 ranks as the biggest margin to beat a monthly record by in both the NOAA and NASA databases.

Departure of temperature from average for July 2023
Figure 2. Departure of temperature from average for July 2023, the warmest July for the globe since record-keeping began in 1850. Record-warm temperatures covered just over 9.3% of the world’s surface , which marks the highest July percentage since records began. (Image credit: NOAA/NCEI)

According to an analysis by Climate Central, over 6.5 billion people — 81% of the global population — experienced at least one day in July with temperatures that were made at least three times more likely by human-caused global warming (a Climate Shift Index of at least three — the index ranges from -5 to +5 with positive levels indicating temperatures that are becoming more likely due to climate change). More than 2 billion people experienced a Climate Shift Index of at least three during all 31 days of July.

Land areas had their warmest July on record in 2023, with global ocean temperatures also the warmest, according to NOAA. July was the fourth consecutive month with record-high global ocean temperatures. Asia, Africa, and South America each had their warmest July on record; North America, its second-warmest; Europe, its eighth-warmest; and Oceana, its 11th-warmest. As reported in our post last week, July ranked as the 11th-warmest July on record in the United States. Temperatures in the North Atlantic and Gulf of Mexico during July were particularly extreme, and the Caribbean, Central America, and Mexico had their warmest July on record.

The year-to-date period of January-July is the third-warmest on record globally. And according to NOAA’s latest Global Annual Temperature Rankings Outlook and the statistical model it uses, there’s a 47% chance of 2023 being the warmest year on record; this is a boost from the odds given last month, which were put at 20%. Note that this NOAA outlook is based purely on statistical comparison to past temperature trends and uses no forward-looking weather or climate model guidance, so it may still be an underestimate. Berkeley Earth puts the odds of 2023 beating 2016 as the warmest year on record at over 99%; climate scientist Zeke Hausfather gives at least an 85% chance. He expects that 2024 will be even warmer than 2023, because of the influence of an intensifying El Niño event in the eastern Pacific.

Using NASA data, 2023 was 1.41°C above the temperature of the 1880-1899 period, which is commonly called “pre-industrial” (the difference between the 1951-1980 baseline reported on the NASA website and the 1880-1899 period is 0.226°C). While 2023 is not expected to be 1.5°C warmer than the preindustrial climate – the target threshold for the stabilization of the long-term climate agreed upon in international climate negotiations – it is possible that 2024 might, according to Hausfather. This would very likely be just a temporary exceedance of the 1.5°C threshold, but the planet may start regularly exceeding this mark by the 2030s, especially if major emission cuts are not implemented by then.

After experiencing its warmest May and June on record, Canada also had its warmest July, helping boost a record wildfire season. Multiple large incursions of Canadian wildfire smoke degraded air quality in the U.S. during July.

El Niño intensifies

El Niño conditions strengthened over the past month in the eastern tropical Pacific, and were at moderate strength, based on sea surface temperatures in the Niño-3.4 region (about 1.1 degree Celsius above average over the past week). In NOAA’s August 10 discussion, they gave a two-thirds chance of the current event becoming a strong El Niño by the November-January period, with “strong” defined as a seasonally averaged Niño-3.4 sea surface temperature more than 1.5 degree Celsius above average.

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 1% chance of neutral conditions, and a 99% 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. NOAA’s latest seasonal forecast, issued August 10, called for a 60% chance of an above-normal Atlantic hurricane season.

Arctic sea ice: 12th-lowest July extent on record

Arctic sea ice extent during July 2023 was the 12th-lowest in the 45-year satellite record, according to the National Snow and Ice Data Center. The shipping channels through the Northwest Passage through Canadian waters and through the Northeast Passage north of Russia remained closed to ice-free navigation.

Antarctic sea ice: lowest on record

Antarctic sea ice extent in July was by far the lowest on record, the third-consecutive month with a record low. Whereas Antarctic sea ice typically grows from a winter minimum extent of around 3 million square kilometers to around 17 million sq. km. by the end of July, this year’s extent as of July 31 had risen to only 14.6 million sq. km, according to data from the National Snow and Ice Data Center.

According to NSIDC, “there is speculation that the Antarctic sea ice system has entered a new regime, in which ocean heat is now playing a stronger role in limiting autumn and winter ice growth and enhancing spring and summer melt. While this very low extent has garnered much attention, as well as consternation, a study led by colleague Dave Gallaher several years ago provides evidence from early Nimbus satellite data that sea ice extent in the winter of 1966 may have rivaled the very low level seen today. A second information source, from a reconstruction of Antarctic sea ice led by Ryan Fogt, a professor at Ohio University, suggests that the present level is well below anything seen since the earliest Southern Ocean weather observations, back to 1905.”

Antarctic land ice – which contributes to sea level rise when it melts – has seen accelerated melting in recent years, according to an August 8 paper, Antarctic extreme events. In an interview with The Guardian, co-author Dr. Anna Hogg of the University of Leeds said the rate of ice sheet loss from Antarctica “matches the IPCC worst case” for predicted ice loss under high greenhouse gas emissions scenarios. The observations show we’re tracking [along] the most extreme prediction of what might happen.” This is despite global greenhouse gas emissions currently tracking closer to an intermediate emissions pathway.

Greenland: warmest July on record causes near-record melting

Greenland experienced its warmest July on record, which caused the Greenland Ice Sheet to suffer extensive melting. According to the National Snow and Ice Data Center, the extent of surface melt during July was close to the previous records in the summers of 2012 and 2019.

Notable global heat and cold marks for July 2023

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

  • Hottest temperature in the Northern Hemisphere: 53.9°C (129.0°F) at Saratoga Spring, Calif., (USA), July 16;
  • Coldest temperature in the Northern Hemisphere: -22.9°C (-9.2°F) at Summit, Greenland, July 16;
  • Hottest temperature in the Southern Hemisphere: 40.1°C (104.2°F) at Balsas, Brazil, July 14; and
  • Coldest temperature in the Southern Hemisphere: -83.2°C (-117.8°F) at Concordia, Antarctica, July 25.

Major weather stations in July: 131 all-time heat records, no all-time cold records

Among global stations with a record of at least 40 years, 131 set, not just tied, an all-time heat record in July, and no stations set an all-time cold record:

Zhaitang (China) max. 41.3°C, July 1;
Bam (Iran) max. 48.6°C, July 1;
Kuujjuak (Canada) max. 34.3°C, July 4;
Inuvik (Canada) max. 33.0°C, July 4;
Chapais (Canada) max. 35.8°C, July 6;
Sanhe (China) max. 41.3°C, July 6;
Huairou (China) max. 41.3°C, July 6;
Jingxing (China) max. 43.3°C, July 6;
Gaizhou (China) max. 37.4°C, July 6;
Linzhou (China) max. 43.3°C, July 7;
Jincheng (China) max. 38.8°C, July 7;
Carmacks (Canada) max. 35.5°C, July 7;
Fort Good Hope (Canada) max. 37.4°C, July 8;
Norman Wells (Canada) max. 37.9°C, July 8;
Wenxian (China) max. 39.8°C, July 9;
Pengyang (China) max. 35.4°C, July 9;
Ufa (Russia) max. 39.4°C, July 10;
Birsk (Russia) max. 39.1°C, July 10;
Chlef (Algeria) max. 48.3°C, July 10;
Bejaia (Algeria) max. 44.8°C, July 10;
Sallanches (France) max. 40.2°C, July 11;
Pinares de Mayari (Cuba) max. 33.8°C, July 11;
Bludenz (Austria) max. 37.7°C, July 11;
Sonnblick (Austria) max. 15.7°C, July 11;
Sadrinsk (Russia) max. 40.0°C, July 11;
Yekaterineburg (Russia) max. 40.0 °C, July 11;
Kurgan (Russia) max. 41.2 °C, July 11;
Magnitogorsk (Russia) max. 39.1 °C, July 11;
Perm (Russia) max. 37.5 °C, July 11;
Nozovka (Russia) max. 37.7 °C, July 11;
Krasnoufimsk (Russia) max. 37.9 °C, July 11;
Samary (Russia) max. 37.8 °C, July 11;
Verhnij Ufalej (Russia) max. 37.5 °C, July 11;
Yalturovsk (Russia) max. 38.2 °C, July 11;
Poltavka (Russia) max. 40.9°C, July 12;
Slavgorod (Russia) max. 40.7°C, July 12;
Karasuk (Russia) max. 39.9°C, July 12;
Kupino (Russia) max. 39.6°C, July 12;
Zdvinsk (Russia) max. 39.0°C, July 12;
Isim (Russia) max. 38.7°C, July 12;
Esil (Kazakhstan) max. 41.6°C, July 12;
Arkalyk (Kazakhstan) max. 42.6°C, July 12;
Zhaltyr (Kazakhstan) max. 41.0°C, July 12;
Akkol (Kazakhstan) max. 39.3°C, July 12;
Semijarka (Kazakhstan) max. 42.6°C, July 14;
Isabel Rubio (Cuba) max. 36.5°C, July 14;
Kingman (Arizona, USA) max. 45.6°C, July 15;
Huadu (China) max. 39.6°C, July 15;
Sihui (China) max. 39.3°C, July 15;
Dongguan (China) max. 38.9°C, July 15;
Sanbao (China) max. 52.2°C, July 16: New national record high for China;
Hirono (Japan) max. 37.3°C, July 16;
Nasu (Japan) max. 33.2°C, July 16;
Kuroiso (Japan) max. 35.4°C, July 16;
Sachs Harbour (Canada) max. 24.8°C, July 17;
Las Vegas (New Mexico, USA) max. 37.8°C, July 18;
Roma Macao (Italy) max. 42.9°C, July 18;
Capo Caccia (Italy) max. 42.4°C, July 18;
Perdasdefogu (Italy) max. 42.6°C, July 18;
Alghero (Italy) max. 42.7°C, July 18;
Castirla (France) max. 42.8°C, July 18;
Belcaire (France) max. 36.4°C, July 18;
Tiranges (France) max. 40.6°C, July 18;
Avrieux (France) max. 36.0°C, July 18;
St Martin de Belleville (France) max. 32.4°C, July 18;
Isola 2000 (France) max. 29.4°C, July 18;
La Chapelle (France) max. 33.4°C, July 18;
Cele (China) max. 42.4°C, July 19;
Chabuchaer (China) max. 40.3 °C, July 19;
Ceuta (Spain) max. 40.8 °C, July 19;
Cannes (France) max. 39.2 °C, July 19;
Guira de Melena (Cuba) max. 37.2°C, July 21;
Owen Int. AP (Cayman Islands,UK) max. 35.3°C, July 21: New territorial record for the Cayman Islands;
Guira de Melena (Cuba) max. 37.1°C, July 22;
Bainoa (Cuba) max. 36.5°C, July 23;
Algiers (Algeria) max. 48.7°C, July 23;
Palermo (Italy) max. 47.0°C, July 24;
Ustica (Italy) max. 43.0 °C, July 24;
Decimomannu (Italy) max. 46.8 °C, July 24;
Cagliari (Italy) max. 44.6 °C, July 24;
Olbia (Italy) max. 47.4 °C, July 24;
Capo San Lorenzo (Italy) max. 47.0 °C, July 24;
Capo Bellavista (Italy) max. 45.0 °C, July 24;
Skikda (Algeria) max. 49.0 °C, July 24;
Annaba (Algeria) max. 48.2 °C, July 24;
Tunis (Tunisia) max. 49.0°C, July 24;
Batabano (Cuba) max. 36.4°C, July 24;
Santiago de las Vegas (Cuba) max. 35.7°C, July 24;
Kucova (Albania) max. 44.0°C, July 25: New national record high for Albania;
Elbasan (Albania) max. 43.2 °C, July 25;
Tirana (Albania) max. 43.0 °C, July 25;
Vlora (Albania) max. 42.2 °C, July 25;
Durres (Albania) max. 41.0 °C, July 25;
Lamezia (Italy) max. 42.7 °C, July 25;
Gabes (Tunisia) max. 49.1 °C, July 25;
Monastir (Tunisia) max. 48.3°C, July 25;
Natashquan (Canada) max.  29.0°C, July 25;
Tarumi (Japan) max. 37.8°C, July 26;
Otsu (Japan) max. 38.4°C, July 26;
Skyros (Greece) max. 44.4°C, July 26;
Syros (Greece) max. 40.7°C, July 26;
Izmir (Turkey) max. 43.2°C, July 26;
Florya (Turkey) max. 40.5°C, July 26;
Golcuk (Turkey) max. 43.4°C, July 26;
Hirakata (Japan) max. 39.8°C, July 27;
Miyama (Japan) max. 37.7°C, July 27;
Takano (Japan) max. 35.1°C, July 27;
Beni Abbes (Algeria) max. 49.4°C, July 27;
Errachidia (Morocco) max. 44.7°C, July 27;
Fuchu (Japan) max. 38.7°C, July 28;
Naomahou (China) max. 45.3°C, July 28;
Midelt (Morocco) max. 39.5°C, July 28;
Kikonai (Japan) max. 34.2°C, July 29;
Yoneyama (Japan) max. 37.1°C, July 29;
Koriyama (Japan) max. 36.5°C, July 29;
M’ Sila (Algeria) max. 47.7 °C, July 29;
Bechar (Algeria) max. 45.9 °C, July 29;
Tebessa (Algeria) max. 44.4 °C, July 29;
Medenine (Tunisia) max. 49.1 °C, July 29;
Sidi Bouzid (Tunisia) max. 47.6 °C, July 29;
Thala (Tunisia) max. 43.4°C, July 29;
Kashimadai (Japan) max. 36.4°C, July 30;
Shinagawa (Japan) max. 35.4°C, July 30;
Shiroishi (Japan) max. 36.9°C, July 30;
Ikari (Japan) max. 35.1°C, July 30;
Touggourt (Algeria) max. 50.3°C, July 30;
Ghardaia (Algeria) max. 48.5°C, July 30;
Remada (Tunisia) max. 48.5 °C, July 30;
Omoto (Japan) max. 36.9°C, July 31;
Tindouf (Algeria) max. 48.9°C, July 31; and
New Iberia (Louisiana, USA) max. 40.0°C, July 31.

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

As of the end of July, nine nations or territories had set or tied an all-time national heat record in 2023; four such records were set in July:

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);
Chad: 48.0°C (118.4°F) at Faya, May 25;
China: 52.2°C (126°F) at Sabao, July 16;
Vatican City: 42.9°C (109.2°F) at Roma Macao, July 18;
Cayman Islands: 35.3°C (95.5°F) at Owen Roberts Airport, July 22; and
Albania: 44.0°C (111.2°F) at Kucova, July 25.

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

As of the end of July 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).

Sixty-five additional monthly national/territorial heat records and four additional monthly cold records beaten or tied

In addition to the nine all-time heat records listed above (plus one, for the records set in two different months in Laos), 65 additional monthly all-time heat records have been set in 2023, for a total of 75 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 (12): Cabo Verde, Botswana, Turkmenistan, Mauritius, Antigua and Barbuda, Spain, Morocco, Portugal, Andorra, Saba, St. Barthelemy, Laos
  • May (9): Mauritius, Solomon Islands, Botswana, Cambodia, Cocos Islands, Panama, Saba, Maldives, French Guiana
  • June (14): Botswana, Vietnam, Tuvalu, Hong Kong, Mauritius, Aruba, Saba, Senegal, Costa Rica, China, Chad, Solomon Islands, Morocco, French Guiana
  • July (10): Mauritius, Liechtenstein, US Virgin Islands, Dominica, Italy, Malta, El Salvador, Tanzania, St. Barthelemy, Martinique

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

  • Feb. (1): Montenegro
  • March (2): St. Eustatius, Martinique
  • June (1): Finland

Hemispherical and continental temperature records through July 2023

  • Lowest temperature reliably recorded in January in the Southern Hemisphere: -51.2°C (-60.2°F) at Concordia, Antarctica, Jan. 31;
  • Highest temperature ever recorded in April in Europe: 38.8°C (101.8°F) at Cordoba, Spain, April 27;
  • Highest temperature ever recorded in July in Europe: 48.2°C (118.8°F) at Jerzu and Lotzorai, Italy, July 24; and
  • Highest minimum temperature ever recorded in July in Europe: 36.2°C (97.2°F) at Palermo, Italy, July 24.

Bob Henson contributed to this post.

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