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Last month was by far the world’s hottest October on record » Yale Climate Connections

October 2023 was the hottest October on record globally in analyses dating back to 1850, said NOAA’s National Centers for Environmental Information on November 15. NOAA, NASA, the Japan Meteorological Agency, and the European Copernicus Climate Change Service all rated October 2023 as the warmest October on record, crushing the previous October record by a huge margin.

world map showing hot temperatures nearly everywhere
Figure 1. Departure of temperature from average for October 2023, the hottest October for the globe since recordkeeping began in 1850. Record-warm temperatures covered nearly 11% of the world’s surface, which was the highest percentage for October since this statistic began being computed in 1951. Less than 1% of the world’s surface had a record-cold October. (Image credit: NOAA/NCEI)

According to NOAA, October global temperatures spiked to a remarkable 1.34 degrees Celsius (2.41°F) above the 20th-century average. Using NASA data, October 2023 was 1.57 degrees Celsius above the temperature of the 1880-1899 period, which is commonly called “preindustrial” (the difference between the 1951-1980 baseline reported on the NASA website and the 1880-1899 period is 0.226°C). This is the fourth-highest departure from average in the NASA database, behind September 2023 (1.70°C), February 2016 (1.59°C), and March 2016 (1.58°C).

Land and ocean areas each had their warmest October on record in 2023, and October was the seventh consecutive month with record-high global ocean temperatures. South America and Asia had their warmest October on record; North America, Africa, and Europe had their second-warmest October; Oceania had its 15th-warmest October. The month ranked as the 18th-warmest October on record in the United States.

The record-smashing heat was not limited to Earth’s surface. In the upper atmosphere, October had the largest departure from average of any month since satellite measurements began: 0.93 degree Celsius above the 1991-2020 average. The previous record was set just last month (0.90 degree Celsius above the 1991-2020 average).

October 2023 was also the wettest October on record globally in terms of moisture in the atmosphere (see Tweet below).

November 2022-October 2023: the hottest 12-month period on record

According to an analysis published last week by Climate Central, the past 12 months (November 2022-October 2023) was 1.3 degrees Celsius above the pre-industrial climate. It ranked as the hottest 12-month period for around 125,000 years, since before the most recent ice age.

About one in four people worldwide (1.9 billion people) faced extreme and dangerous heatwaves driven by climate change over the last 12 months, and 90% of people experienced at least 10 days of high temperatures that climate change made significantly more likely.

2023 virtually certain to be Earth’s warmest year on record

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October was the fifth consecutive month with record global warmth, and the year-to-date period of January-October is the warmest on record globally. According to NOAA’s latest Global Annual Temperature Rankings Outlook and the statistical model it uses, there’s a greater than 99.5% chance of 2023 being the warmest year on record. At the start of this year, few experts foresaw 2023 as being a contender for Earth’s warmest year, as the bulk of El Niño’s warming comes during the second year of each El Niño rather than the first — so it’s possible that 2024 will be even warmer than this year. The annual average for 2023 will come close to the closely watched threshold of 1.5°C above the preindustrial climate, but it may not quite reach that threshold.

Read: Can we still avoid 1.5 degrees C of global warming?

El Niño moves into the “strong” category

El Niño conditions intensified over the past month in the eastern tropical Pacific and had exceeded the “strong” threshold, according to NOAA’s November 9 discussion. Sea surface temperatures in the Niño-3.4 region in the week ending October 12 were 1.8 degrees Celsius above average; a “strong” El Niño event is defined when these sea surface temperatures are in excess of 1.5 degrees Celsius above average. NOAA gave a greater than 55% chance of the current event being defined as a strong El Niño for the January-March period and a 35% chance of a “historically strong” event rivaling 2015-16 and 1997-98, with sea surface temperatures in the Niño-3.4 region at least 2 degrees Celsius above average during November-January. The forecasters gave an 62% chance that El Niño conditions would continue into April-June 2024.

There is some uncertainty over how impacts will manifest with this event as compared to other strong El Niño events, such as 1982-83, 1997-98, and 2015-16, because there are also exceptionally warm waters in the Northwest Pacific associated with a negative phase of the Pacific Decadal Oscillation, or PDO, and a negative PDO tends to favor La Niña-like versus El Niño-like conditions.

Arctic sea ice: seventh-lowest October extent on record

Arctic sea ice extent during October 2023 was the seventh-lowest in the 45-year satellite record, according to the National Snow and Ice Data Center. The Arctic had its fifth-warmest October on record, according to NOAA.

Antarctic sea ice: lowest on record

Antarctic sea ice extent in October was by far the lowest on record, and was the sixth consecutive month with a record low.

According to an October 27 paper in Science Advances, the Denman Glacier in East Antarctica will contribute 0.33 mm per year to global sea level rise until the year 2300 — a level that is about half of the current sea level contribution of the entire Antarctic ice sheet.

Notable global heat and cold marks for October 2023

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

  • Hottest temperature in the Northern Hemisphere: 46.8°C (116.2°F) at Ab Bakhsh, Iraq, October 4
  • Coldest temperature in the Northern Hemisphere: – 49.5°C (-57.1°F) at Summit, Greenland, October 15
  • Hottest temperature in the Southern Hemisphere: 46.5°C (115.7°F) at Villamontes, Bolivia, October 16
  • Coldest temperature in the Southern Hemisphere: -74.9°C (-102.8°F) at Vostok, Antarctica, October 7
  • Highest 2023 average temperature to date in the Northern Hemisphere (Jan-Oct): 32.9°C (91.2°F) at Matam, Senegal
  • Highest 2023 average temperature to date in the Southern Hemisphere (Jan-Oct): 29.5°C (85.1°F) at Floriano, Brazil; Surabaya AP, Indonesia; and Garissa, Kenya.

Major weather stations in October: 25 all-time heat records, no all-time cold records

Among global stations with a record of at least 40 years, 25 set, not just tied, an all-time heat record in October, and no stations set an all-time cold record:

Timerhi Airport (Guyana) max. 38.3°C, October 1
Manaus (Brazil) max. 39.7°C, October 2
Tarapoto (Peru) max. 40.2°C, October 2
Cobija (Bolivia) max. 40.0°C, October 6
Inapari (Peru) max. 41.6°C, October 7: New national record high for Peru;
Potosi Airport (Bolivia) max. 25.5°C, October 11
St Laurent do Moroni (French Guiana) max. 38.9°C, October 14
Grand Santi (French Guiana) max. 39.1°C, October 1:  New territorial record high for French Guiana
Pirlangimpi (Australia) max. 38.8°C, October 15
Asuncion Airport (Paraguay) max. 43.0°C, October 16
San Pedro (Paraguay) max. 43.0°C, October 16
Mindelo (Cape Verde) max. 36.2°C, October 16
Porto Murtinho (Brazil) max. 43.4°C, October 17
San Jose (Bolivia) max. 43.7°C, October 19
San Joaquin (Bolivia) max. 41.7°C, October 19
Magdalena (Bolivia) max. 40.6°C, October 19
Cuiaba (Brazil) max. 44.2°C, October 19
Diamantino (Brazil) max. 42.6°C, October 20
Trinidad (Bolivia) max. 41.5°C, October 22
San Borja (Bolivia) max. 42.0°C, October 22
Santa Cruz Airport (Bolivia) max. 41.4°C, October 22
San Ramon (Bolivia) max. 40.4°C, October 23
Nueva Asuncion (Paraguay) max. 44.7°C, October 23
Cabrobo (Brazil) max. 40.4°C, October 26

Maevatanana (Madagascar) max. 40.1°C, October 26.

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

As of the end of October, 21 nations or territories had set or tied an all-time national heat record in 2023; two of these records were set in October. Four nations or territories — the U.S. Virgin Islands, Chad, Saba, and Peru — beat or tied their old all-time heat record twice in 2023; French Guiana has beaten their previous all-time heat record three times; and Laos has beaten its previous all-time heat record an astounding four times. According to Herrera, the record for most national/territorial all-time heat records in a year is 24, set in 2019. Here are the ones set so far 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);
Chad: 48.0°C (118.4°F) at Faya, May 25; tied again on June 16;
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;
Albania: 44.0°C (111.2°F) at Kucova, July 25;
Morocco: 50.4C (122.7°F) at Agadir, August 11;
U.S. Virgin Islands (USA): 35.6°C (96.1°F) at St. Croix, August 14 (tie); beaten on September 9 with 36.1°C (97°F) at St. Croix;
Dominica: 36.6°C (97.9°F) at Canefield Airport, August 27;
Aruba: 36.5°C (97.7°F) at Queen Beatrix Airport, August 28 (tie);
Saba: 34.4°C (93.9°F) at Juancho Yrausquin Airport, August 29; tied again on September 8;
Martinique (France): 36.6°C (97.9°F) at Ducos, September 15;
St. Barthelemy (France): 35.5°C (95.9°F) at Gustavia, September 15 (tie);
French Guiana (France): 38.1°C (100.6°F) at Grand Santi. September 15; beaten on September 25 with 38.8°C (101.8°F) at St. Laurent do Moroni; beaten again with 39.1°C (102.4°F) at Grand Santi, October 14;
Guyana: 40.1°C (104.2°F) at Ebini, September 26;
Peru: 41.4°C (106.5°F) at Tingo de Ponaza, September 27; beaten again with 41.6°C (106.9°F) at Inapari, October 7;
Suriname: 38°C (100.4°F) at Zanderj Airport, September 30 (tie); and
Barbados: 35.6°C (96.1°F) at Bridgetown, September 30.

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

As of the end of October 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).

One hundred fourteen additional monthly national/territorial heat records and six additional monthly cold records beaten or tied in 2023

In addition to the 21 all-time heat records listed above (plus six, for the records set in two different months in Laos, Chad, Saba, French Guiana, Peru, and the U.S. Virgin Islands), 114 additional monthly all-time heat records have been set in 2023, for a total of 141 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 (15): Botswana, Vietnam, Tuvalu, Hong Kong, Mauritius, Aruba, Saba, Senegal, Costa Rica, China, Chad, Solomon Islands, Morocco, French Guiana, Guyana
  • July (11): Mauritius, Liechtenstein, US Virgin Islands, Dominica, Italy, Malta, El Salvador, Tanzania, St. Barthelemy, Martinique, Guyana
  • August (17): Qatar, Niger, Mauritius, Chile, St. Barthelemy, Turkey, Thailand, Botswana, France, Bolivia, Paraguay, Martinique, Chad, Suriname, French Guiana, US Virgin Islands, Kenya
  • September (8): Saba, Mauritius, Chad, Norway, St. Barthelemy, Djibouti, French Guiana, Peru
  • October (22): Spain, Andorra, Saba, Guyana, France, Austria, Poland, Taiwan, Oman, Iran, Slovenia, Mauritius, Singapore, Colombia, US Virgin Islands, Dominican Republic, Belize, Honduras, Senegal, Moldova, Paraguay, Dominica

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

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

Hemispherical and continental temperature records through October 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 minimum temperature ever recorded in Africa for any month: 39.6°C (103.3°F) at Adrar, Algeria, July 6;
Highest temperature ever recorded in July in Europe: 48.2°C (118.8°F) at Jerzu and Lotzorai, Italy, July 24;
Highest minimum temperature ever recorded in July in Europe: 36.2°C (97.2°F) at Palermo, Italy, July 24;
Highest temperature ever recorded in Africa in August (tie): 50.4°C (122.7°F) at Agadir, Morocco, August 11;
Highest temperature ever recorded in the Southern Hemisphere in August (tie): 45.0°C (113°F) at Villamontes, Bolivia, August 23;
Highest minimum temperature ever recorded in Oceania and in the whole Southern Hemisphere in August: 28.8°C (83.8°F) at Funafuti, Tuvalu, August 31 (previous record: 28.7°C at August Nui, Tuvalu, on August 14);
Highest minimum temperature ever recorded in South America and the Southern Hemisphere in September: 30.6°C (87.1°F) at Base Aerea Jara, Paraguay, September 3;
Highest minimum temperature ever recorded in the world in October: 33.9°C (93.0°F) at Abu al Bukoosh (United Arab Emirates), October 6; and
Highest minimum temperature ever recorded in South America in October: 31.6°C (88.9°F) at Nueva Asuncion (Paraguay), October 23.

Bob Henson contributed to this post.

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