The first month of 2025 was Earth’s warmest January in analyses of global weather data going back to 1850, NOAA’s National Centers for Environmental Information, or NCEI, reported Feb. 12. NASA also rated January 2025 as the warmest January on record, 1.59 degrees Celsius (2.86 °F) above the 1880-1899 period, which is its best estimate for when preindustrial temperatures occurred. This beat the previous record from January 2024 by 0.12 degrees Celsius (0.22 °F). The European Copernicus Climate Change Service and Berkeley Earth also rated January 2025 as the warmest January on record.
Global land areas had their warmest January on record in 2025, and global oceans had their second-warmest January, according to NOAA. Oceana had its second-warmest January; Europe and Asia had their third-warmest January; South America, its fourth-warmest; Africa its fifth-warmest; and North America, its 10th-warmest.
The contiguous U.S. had below-average temperatures in January, recording it’s coldest January since 1988, and its coldest month relative to average since December 2000.
An unexpected record
The January record was surprising since it beat the previous record set just last year. At that point, a strong El Niño event was in full force, boosting global temperatures. But in January 2025, cooler than average temperatures were present in the Eastern Pacific, thanks to what NOAA classified as a weak La Niña event. It is very unusual to beat a monthly temperature record during a La Niña event. Climatologist Brian Bretschneider (see skeet below) noted that the three previous warmest Januarys all occurred during El Niño events when warm ocean waters in the Eastern Pacific helped bump global temperature higher by about 0.2 degree Celsius.
However, the current La Niña event is weak. The Australian Bureau of Meteorology does not recognize it, saying that we are currently in ENSO-neutral conditions, despite changes in sea surface temperature patterns consistent with a developing La Niña. (Keep in mind that the bureau uses a more stringent threshold for La Niña conditions than NOAA does. Sea surface temperatures must be at least 0.8 degree Celsius below the seasonal average in the key Niño3.4 region of the eastern tropical Pacific, versus the 0.5-degree threshold used by NOAA.)
One reason for the record January 2025 warmth was that Earth’s surface (in regions where clouds were not present) was unusually non-reflective, setting a record for the lowest albedo (reflectivity) on record (see skeet below). This allowed the surface to absorb more solar energy than usual, helping drive the record warmth.
Below-average snow cover in Europe and Asia was partially responsible for this low albedo; Northern Hemisphere snow cover during January 2025 was the fourth-lowest since records began in 1967. We don’t know what role sparser-than-usual cloud cover may have played in the January temperature record, but during 2023, reduced cloud cover helped drive the year’s record warmth (see skeet below).
Weak La Niña event expected to end by spring
A weak La Niña event began in December, NOAA reported in its January monthly discussion of the state of the El Niño/Southern Oscillation, or ENSO (a new update is scheduled to be released Feb. 13). If the event persists for five overlapping three-month periods, or long enough to qualify as a La Niña episode, it will be the latest-starting episode in NOAA records going back to 1950.
According to NOAA’s January forecast, La Niña conditions are expected to persist through February-April 2025 (59% chance), with a transition to ENSO-neutral likely during March-May 2025 (60% chance). For the upcoming Atlantic hurricane season (August-September-October), the Jan. 21 Columbia University International Research Institute for Climate and Society forecast called for a 44% chance of La Niña, a 43% chance of ENSO-neutral, and a 13% chance of El Niño. El Niño conditions tend to suppress Atlantic hurricane activity through an increase in wind shear, but La Niña conditions tend to have the opposite effect.
While El Niño events often 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.
Arctic sea ice: 2nd–lowest January extent on record
Arctic sea ice extent during January 2025 was the second-lowest in the 46-year satellite record, behind only January 2018, according to the National Snow and Ice Data Center, or NSIDC. The January mark follows a December that had record-low sea ice extent. So far in February, sea ice extent has set new record lows each day, beating out the previous record lows from 2018. The Arctic had its fourth-warmest January on record in 2025.
A record melt day in Antarctica
On January 2, 2025, 3.7% of the surface of the Antarctic ice sheet melted. According to NSIDC, this was the most widespread melt event of any day in the 46-year satellite record, beating the all-time record of 3.3% set just a week earlier in December. For the month as a whole, Antarctic sea ice extent was only slightly below average, well above the record-low values of 2023. However, by the end of January, sea ice extent ranked in the lowest 10% of daily values. The Antarctic seasonal maximum typically occurs in late February or early March. The Antarctic had its 36th-warmest January on record in 2025.
Notable global heat and cold marks for January 2025
Weather records expert Maximiliano Herrera has characterized the level of heat records that have been set thus far in 2025 as more characteristic of El Niño conditions, not La Niña. Below are some of the records he documented in January. Follow him on Bluesky: @extremetemps.bsky.social or Twitter: @extremetemps:
– Hottest temperature in the Northern Hemisphere: 40.5°C (104.9°F) at Sarh, Chad, Jan. 19;
– Coldest temperature in the Northern Hemisphere: -61.0°C (-77.8°F) at Summit, Greenland, Jan. 16;
– Hottest temperature in the Southern Hemisphere: 49.3°C (120.7°F) at Geraldton, Australia, Jan. 20; and
– Coldest temperature in the Southern Hemisphere: -46.5°C (-51.7°F) at Concordia, Antarctica, Jan. 31.
Major weather stations in January: 4 all-time heat records, 4 all-time cold records
Among global stations with a record of at least 40 years, four set, not just tied, an all-time heat record in January, and four stations set an all-time cold record:
Trelew (Argentina) max. 43.6°C, January 12;
La Roche (New Caledonia, France) max. 35.3°C, January 17;
Kalbarri (Australia) max. 48.3°C, January 20;
Jarrahwood (Australia) max. 43.7°C, January 20;
New Iberia (Louisiana, USA) min. -16.7°C, January 22;
Lafayette (Louisiana, USA) min. -15.6°C, January 22;
New Roads (Louisiana, USA) min. -15.6°C, January 22; and
Jennings (Louisiana, USA) min. -13.9°C, January 22.
Six nations or territories have set monthly all-time heat records in 2025:
– Jan. (6): Cocos Islands. French Southern Territories, Faroe Islands, Maldives, Northern Marianas, Martinique
One nation set an all-time monthly cold record in January: Qatar.
Bob Henson contributed to this post.
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