Monthly climate report
Climate report: May 2025
Global land temperature (NASA GISTEMP v4) and atmospheric CO₂: where things stand at the end of May 2025.
Global temperature in May 2025
- May 2025 (land)
- +1.70 °Cversus 1901–1930
- Rank of the month
- 2ndof 146 Mays on record
- 2025, January–May
- +2.21 °C1st of 146 years
- 12-month average
- +2.15 °C12 months ending May 2025
In May 2025, land areas worldwide were +1.70 °C warmer than the 1901–1930 average, according to NASA's GISTEMP v4 analysis, compared with +1.79 °C in May 2024. That makes it the 2nd warmest May in 146 years of records. The record for this month remains May 2024 (+1.79 °C).
From January to May, 2025 averages +2.21 °C — the warmest start to a year since 1880.
Over the 12 months ending in May 2025, the land average is +2.15 °C, against +2.13 °C over the previous 12 months. The highest 12-month average remains the one ending in August 2024 (+2.21 °C).
Every month since June 2023 has been more than 1.5 °C above the 1901–1930 average — 24 months in a row.
These figures cover land areas only. Land warms faster than the ocean, so the values are higher than the combined land-and-ocean averages usually quoted.
The last 13 months
| Month | Anomaly vs 1901–1930 |
|---|---|
| May 2025 | +1.70 °C |
| April 2025 | +2.23 °C |
| March 2025 | +2.53 °C |
| February 2025 | +2.07 °C |
| January 2025 | +2.56 °C |
| December 2024 | +2.38 °C |
| November 2024 | +2.01 °C |
| October 2024 | +2.16 °C |
| September 2024 | +1.95 °C |
| August 2024 | +2.25 °C |
| July 2024 | +1.93 °C |
| June 2024 | +2.08 °C |
| May 2024 | +1.79 °C |
The 10 warmest Mays on record
Land areas, 1880–2025.
| # | Year | Anomaly vs 1901–1930 |
|---|---|---|
| 1 | May 2024 | +1.79 °C |
| 2 | May 2025this report | +1.70 °C |
| 3 | May 2020 | +1.69 °C |
| 4 | May 2012 | +1.62 °C |
| 5 | May 2017 | +1.62 °C |
| 6 | May 2014 | +1.57 °C |
| 7 | May 2007 | +1.56 °C |
| 8 | May 2016 | +1.55 °C |
| 9 | May 2018 | +1.50 °C |
| 10 | May 2022 | +1.43 °C |
Atmospheric CO₂
The annual mean rose from 421.08 ppm in 2023 to 424.60 ppm in 2024, +3.5 ppm in one year.
Sources and method
- Temperatures: NASA GISS, GISTEMP v4, monthly mean over land areas, rebased to 1901–1930 (file of November 14, 2026).
- Ranks use the months known at the date of the report. NASA slightly revises past values at each update, so figures can move by a few hundredths of a degree.
- CO₂: NOAA Global Monitoring Laboratory, Mauna Loa Observatory.