May 2025 was the planet’s second-warmest on record

May 2025 was Earth’s second-warmest May in analyses of global weather data going back to 1850, NOAA’s National Centers for Environmental Information, or NCEI, reported June 12. NASA and the European Copernicus Climate Change Service also rated May 2025 as the second-warmest May on record, behind only 2024. Data from the Japan Meteorological Agency and Berkeley Earth were not available at the time of this writing. May 2025 was only the second month in the last 23 months for which the global-average surface air temperature was not more than 1.5 degrees Celsius above pre-industrial levels, according to the European Copernicus Climate Change Service. Prior to the past 23 months, only five months (January-March 2016 and January-February 2020) had previously been above that level.

Departure of temperature from average for May 2025. — Figure 1. Departure of temperature from average for May 2025, the world’s second-warmest May since record-keeping began in 1850. Approximately 7% of the Earth’s surface had record-warm conditions. Only 2024 had a larger percentage with record-warm May temperatures, with 15%. (Image credit: NOAA/NCEI)

Global land areas had their second-warmest May on record in 2025, and global oceans also had their second-warmest May, according to NOAA. Asia and South America had their third-warmest May on record; North America its sixth-warmest; Africa, its seventh-warmest; Europe, Oceania, and the Antarctic region had a warmer-than-average May, but their May temperature did not rank among the 10 warmest Mays on record. Northern Hemisphere snow cover during May 2025 was the 14^th-lowest since 1967.

According to NOAA, the year-to-date-period (Jan-May) has been the second-warmest on record for the globe, behind only 2024. NOAA gave a >99.9% chance that 2025 would wind up as a top-five warmest year on record; a 23% chance of it being the second-warmest year on record; and a less than 1% chance of being the warmest year on record.

Second warmest spring on record globally and in the contiguous U.S.

During meteorological spring (March-May) in the Northern Hemisphere in 2025, the globe had its second-warmest such period on record. The global land-only surface temperature during March-May was the highest on record

The springtime contiguous U.S. average temperature was 3.2°F (1.8°C) above average, making it the second-warmest spring in the 131-year record. North Carolina recorded its second-warmest spring, while Georgia, Louisiana, Maryland, Mississippi, and Virginia each matched or exceeded their third-warmest spring on record.

During May, the average temperature in the contiguous U.S. ranked in the warmest third of historical Mays extending back to 1895. Alabama had its wettest May on record, while Maryland, Pennsylvania, Rhode Island, and Vermont each recorded their second wettest.

U.S. tornadoes in May numbered 333, with 16 being EF2 or stronger. The preliminary total of 1,113 U.S. tornadoes observed from January 1 to June 9 ranks as the third-highest year-to-date total since 2010, behind 2011 (1,736) and 2024 (1,175). May had 27 tornado deaths in the U.S., bringing the tornado death toll for the year so far to 62.

Neutral conditions (neither La Niña nor El Niño) prevail

The weak La Niña conditions in the Eastern Pacific that began in December ended in March, and neutral conditions are now present, NOAA reported in its June monthly discussion of the state of the El Niño/Southern Oscillation, or 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. According to NOAA’s June forecast, ENSO-neutral conditions are likely (82% chance) through August 2025, but we may flip into a La Niña event during the coming Northern Hemisphere winter, with a 41% chance of La Niña and a 48% chance of ENSO-neutral conditions prevailing during the December-February period. For the upcoming Atlantic hurricane season (August-September-October), the May 19 forecast from the Columbia University International Research Institute for Climate and Society called for a 31% chance of La Niña, a 54% chance of ENSO-neutral, and a 15% 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. 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: 7th-lowest May extent on record

Arctic sea ice in May 2025 had the seventh-lowest extent in the 47-year satellite record, according to the National Snow and Ice Data Center, or NSIDC. The Arctic had its fourth-warmest May on record in 2025. A record heat wave in Greenland during May caused unprecedented melting of the island’s ice sheet (see skeet above). According to Friederike Otto of the World Weather Attribution group, without human-caused climate change, such an event would have been “basically impossible”.

Antarctic sea ice extent in May was the fifth-lowest in the 47-year satellite record. The Antarctic had above-average temperatures in May that did not rank in the top ten warmest Mays.

Notable global heat and cold marks for May 2025

Weather records expert Maximiliano Herrera documents world temperature extremes in remarkable detail and has provided us with the following info for May. Follow him on Bluesky: @extremetemps.bsky.social

Hottest temperature in the Northern Hemisphere: 52.2°C (126.0°F) at Abqaiq, Saudi Arabia, May 24
Coldest temperature in the Northern Hemisphere: -39.6°C (-39.3°F) at Summit, Greenland, May 12
Hottest temperature in the Southern Hemisphere: 39.9°C (103.8°F) at Alexander Bay, South Africa, May 16
Coldest temperature in the Southern Hemisphere: -79.6°C (-111.3°F) at Concordia, Antarctica, May 20, and Vostok, Antarctica, May 22

Major weather stations in May: one all-time heat record, one all-time cold record

Among global stations with a record of at least 40 years, one set, not just tied, an all-time heat record in May, and one set an all-time cold record:

Padthaway (Australia) min. -4.5°C, May 19

Saint Louis (Senegal) max. 46.6°C, May 27

Two all-time national/territorial heat records beaten or tied as of the end of May

Maldives: 35.8°C (96.4°F) at Hanimadhoo, Feb. 27 (previous record: 35.1°C (95.2°F) at Hanimadhoo, March 24, 2024
Togo: 44.0°C (111.2°F) at Mango, March 16 and April 5 (tie).

Thirty-one additional monthly national/territorial heat records beaten or tied as of the end of May

In addition to the two all-time national/territorial records set so far in 2025 (plus one nation that tied its record in two separate months), 31 nations or territories have set or tied monthly all-time heat records as of the end of May 2025, for a total of 34 monthly heat records:

January (6): Cocos Islands. French Southern Territories, Faroe Islands, Maldives, Northern Marianas, Martinique
February (3): Northern Marianas, Argentina, Togo
March (6): French Southern Territories, Algeria, Saba, South Korea, Kyrgyzstan, Georgia
April (11): French Southern Territories, British Indian Ocean Territory, Latvia, Estonia, Kuwait, Saudi Arabia, Iraq, Iran, Turkmenistan, Kyrgyzstan, Ireland
May (6): French Southern Territories, Iceland, Kyrgyzstan, China, Qatar, Mauritius

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.