October 2025 was Earth’s third-warmest October in analyses of global weather data going back to 1850, behind only 2023 and 2024, said the European Copernicus Climate Change Service on Nov. 7. The service rated the year-to-date period of January to October the second-warmest such period on record, behind only 2024.
The service reported that 2025 is likely to end up as the second- or third-warmest year on record, possibly tied with 2023 as the second-warmest year (behind only 2024). Because of the U.S. government shutdown, data from NOAA and NASA is not yet available for September or October.
This is the fifth time in a row that a calendar month has placed third for all-time warmth behind 2023 and 2024. While “third-warmest” may not sound eye-poppingly impressive, this comes on the heels of an astoundingly warm couple of years that were fueled by a strong El Niño event atop long-term human-caused warming.
A short-lived La Niña event likely to end in early 2026
The La Niña advisory put into effect in September continues, as the El Niño/Southern Oscillation, or ENSO, remains in a La Niña state, NOAA reported in its October monthly discussion of ENSO. ENSO is a recurring ocean-and-atmosphere pattern that warms and cools the eastern tropical Pacific through El Niño and La Niña events that last from one to three years. To qualify as such a full-fledged event, El Niño or La Niña conditions must persist in both the ocean and atmosphere for at least five consecutive, overlapping three-month periods. The span from September through November is likely to be the first such three-month La Niña period.
According to NOAA’s October forecast, weak La Niña conditions are expected to prevail during the upcoming Northern Hemisphere winter, with a 55% chance of transitioning to ENSO-neutral in January through March 2026. The Oct. 20 forecast from the Columbia University International Research Institute for Climate and Society gave a 50% or greater chance of La Niña conditions lasting through December 2025 through February 2026.
Both of the forecasts above project the odds of El Niño to steadily climb to around 30% by next summer. Notably, the North American Multi-Model Ensemble suggests that sea surface temperatures could be above average, pushing toward borderline El Niño warmth, as soon as next spring (April-May-June). All six of the NMME’s component models now show this trend. With this in mind, it’s worth keeping an eye out for a potential El Niño event in the latter part of 2026, although it’s far too early for a reliable forecast.
While El Niño events typically last only one year (usually from northern fall to northern spring, as in 2023-24), La Niña events often restrengthen or recur across two or even three years in a row, as was the case from mid-2020 to early 2023.
Over the last two decades (2005-2024), the peak three months of hurricane season have included five El Niño periods, seven La Niña periods, and eight neutral periods.
Arctic sea ice: 8th-lowest October extent on record
Arctic sea ice in October 2025 had the 8th-lowest October extent in the 47-year satellite record, according to the National Snow and Ice Data Center, or NSIDC. As of Nov. 7, Arctic sea ice had the third-lowest extent on record for the date, behind only 2016 and 2020.
The Northeast Passage along the coast of Russia and the southern route of the Northwest Passage through Canadian waters are now closed to ice-free navigation, according to ice maps from the U.S. National Ice Center.
Antarctic sea ice extent in October was the third-lowest in the 47-year satellite record. Only 2023 and 2024 had lower October extents.
Both the Arctic and Antarctic set records for having the warmest October temperatures on record.
Notable global heat and cold marks for October 2025
Maximiliano Herrera documents world temperature extremes in remarkable detail and has provided us with the following information for October. Follow him on Bluesky: @extremetemps.bsky.social
- Hottest temperature in the Northern Hemisphere: 46.7°C (116.1°F) at Shabankareh, Iran, October 1
- Coldest temperature in the Northern Hemisphere: -50.0°C (-58.0°F) at Summit, Greenland, October 29
- Hottest temperature in the Southern Hemisphere: 46.1°C (115.0°F) at Birdsville, Australia, October 21
- Coldest temperature in the Southern Hemisphere: -67.6°C (-89.7°F) at Dome Fuji, Antarctica, October 12
Major weather stations in October: two all-time heat records, no all-time cold records
Among global stations with a record of at least 40 years, two set, not just tied, an all-time heat record in October; no stations set an all-time cold record:
Culiacan Airport (Mexico) max. 44.2°C, October 10
Cape Byron (Australia) max. 35.9°C, October 27
Nine all-time national/territorial heat records beaten or tied as of the end of October
- Maldives: 35.8°C (96.4°F) at Hanimadhoo, Feb. 27 (previous record: 35.1°C (95.2°F) at Hanimadhoo, Mar. 24, 2024
- Togo: 44.0°C (111.2°F) at Mango, Mar. 16 and Apr. 5 (tie)
- Turkey: 50.5°C (122.9°F) at Silopi, Jul. 25
- Kosovo: 42.5°C (108.5°F) at Kline, Jul. 25
- Brunei: 39.2°C (102.6°F) at Sukang, Jul. 29; tied again on Aug. 1 at the same location
- Japan: 41.2°C (106.2°F) at Kaibara, Jul. 30; broken again on Aug. 5 with 41.8°C (107.2°F) at Isesaki
- United Arab Emirates: 51.8°C (125.2°F) at Swiehan, Aug. 1 (tie)
- Martinique (territory of France): 37.0°C (98.6°F) at Le Lamentin, Aug. 22
- St. Eustatius (territory of the Netherlands): 34.4°C (93.9°F) at Roosevelt Airport, Sep. 13
Sixty-six additional monthly national/territorial heat records beaten or tied as of the end of October
In addition to the nine all-time national/territorial records set so far in 2025 (plus three nations that beat or tied their record in two separate months), 66 nations or territories have set or tied monthly all-time heat records as of the end of October 2025, for a total of 78 monthly heat records:
- January (6): Cocos Islands. French Southern Territories, Faroe Islands, Maldives, Northern Marianas, Martinique
- February (3): Northern Marianas, Argentina, Togo
- March (8): French Southern Territories, Algeria, Saba, South Korea, Kyrgyzstan, Georgia, Mauritius, Cocos Islands
- April (11): French Southern Territories, British Indian Ocean Territory, Latvia, Estonia, Kuwait, Saudi Arabia, Iraq, Iran, Turkmenistan, Kyrgyzstan, Ireland
- May (5): French Southern Territories, Iceland, Kyrgyzstan, China, Qatar
- June (7): Cocos Islands, Hong Kong, Slovenia, Spain, Portugal, Jersey, French Southern Territories
- July (7): Maldives, Ukraine, Honduras, French Southern Territories, U.S. Virgin Islands, Malaysia, Japan
- August (10): Honduras, Cocos Islands, Lebanon, Albania, French Southern Territories, Israel, Iceland, Grenada, St. Vincent and the Grenadines, Martinique
- September (4): Canada, Namibia, Chile, Central African Republic
- October (5): Taiwan, French Southern Territories, New Caledonia, Cocos Islands, Martinique
One nation set an all-time monthly cold record in 2025: Qatar in January.
Hemispherical and continental temperature records in 2025
- Highest temperature ever recorded in South America in February: 46.5°C (115.7°F) at Rivadavia, Argentina, February 4
- Highest minimum temperature ever recorded in South America in February: 30.8°C (87.4°F) at Catamarca, Argentina, February 10.
Bob Henson contributed to this post.
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