News release

From: World Meteorological Organization (WMO)

WMO confirms 2025 was one of warmest years on record

• Past 11 years have been 11 warmest on record
• Temporary cooling by La Niña does not reverse long-term trend
• Ocean warming continues unabated
• WMO consolidates eight datasets for single authoritative source of information
• International data exchange underpins climate monitoring

The World Meteorological Organization (WMO) has confirmed that 2025 was one of the three warmest years on record, continuing the streak of extraordinary global temperatures. The past 11 years have been the 11 warmest on record, and ocean heating continues unabated.

The global average surface temperature was 1.44 °C (with a margin of uncertainty of ± 0.13 °C) above the 1850-1900 average, according to WMO’s consolidated analysis of eight datasets. Two of these datasets ranked 2025 as the second warmest year in the 176-year record, and the other six ranked it as the third warmest year.

The past three years, 2023-2025, are the three warmest years in all eight datasets. The consolidated three-year average 2023-2025 temperature is 1.48°C (with a margin of uncertainty of ± 0.13 °C) above the pre-industrial era. The past eleven years, 2015-2025, are the eleven warmest years in all eight datasets.

“The year 2025 started and ended with a cooling La Niña and yet it was still one of the warmest years on record globally because of the accumulation of heat-trapping greenhouse gases in our atmosphere. High land and ocean temperatures helped fuel extreme weather – heatwaves, heavy rainfall and intense tropical cyclones, underlining the vital need for early warning systems,” said WMO Secretary-General Celeste Saulo.

“WMO’s state of the climate monitoring, based on collaborative and scientifically rigorous global data collection, is more important than ever before because we need to ensure that Earth information is authoritative, accessible and actionable for all,” said Celeste Saulo.

WMO’s announcement was timed to coincide with the release of global temperature announcements from the dataset providers.

These include the European Center for Medium Range Weather Forecasts Copernicus Climate Change Service (ERA5), Japan Meteorological Agency (JRA-3Q), NASA (GISTEMP v4), the US National Oceanic and Atmospheric Administration (NOAAGlobalTemp v6), the UK’s Met Office in collaboration with the Climatic Research Unit at the University of East Anglia (HadCRUT.5.1.0.0), and Berkeley Earth (USA). This year, for the first time, WMO also factored in two additional datasets - the Dynamically Consistent ENsemble of Temperature (DCENT/UK, USA) and China Merged Surface Temperature Dataset (CMST).

Six of the datasets are based on measurements made at weather stations and by ships and buoys using statistical methods to fill gaps in the data. Two of the datasets – ERA5 and JRA-3Q – are reanalyses which combine past observations, including satellite data, with models to generate consistent time series of multiple climate variables including temperature. The key datasets all use slightly differing methodologies and so have slightly different temperature figures, and even annual rankings.

The actual global temperature in 2025 was estimated to be 15.08°C- however there is a much larger margin of uncertainty on the actual temperature at around 0.5°C than on the temperature anomaly for 2025.

WMO – the UN agency for weather, climate and water - seeks to provide a consolidated authoritative analysis to support decision-making.

Ocean Heat

A separate study published in Advances in Atmospheric Sciences said that ocean temperatures were also among the highest on record in 2025, reflecting the long-term accumulation of heat within the climate system.

About 90% of excess heat from global warming is stored in the ocean, making ocean heat a critical indicator of climate change. From 2024-2025, the global upper 2000 m ocean heat content (OHC) increased by ∼23 ± 8 Zettajoules relative to 2024, according to the study led by Lijing Cheng with the Institute of Atmospheric Physics at the Chinese Academy of Sciences. That’s around 200 times the world’s total electricity generation in 2024.

Regionally, about 33% of the global ocean area ranked among its historical (1958–2025) top three warmest conditions, while about 57% fell within the top five, including the tropical and South Atlantic Ocean, Mediterranean Sea, North Indian Ocean, and Southern Oceans, underscoring the broad ocean warming across basins.

The study found the global annual mean sea surface temperature (SST) in 2025 was 0.49°C above the 1981–2010 baseline and 0.12 ± 0.03°C lower than in 2024, consistent with the development of La Niña conditions, but still ranking as the third-warmest year on record.

Notes for Editors

WMO will provide full details of key climate change indicators, including greenhouse gases, surface temperatures, ocean heat, sea level rise, glacier retreat and sea ice extent, in its State of the Global Climate 2025 report to be issued in March 2026. This will also give details of high-impact events.   

The datasets used by WMO provide a  near-globally complete picture of near surface measurements using statistical methods to fill gaps in data sparse areas such as the polar regions. Reanalyses also provide a globally complete analysis combine past observations, including satellite data, with models to generate consistent time series of multiple climate variables including temperature in all regions.

To calculate the consolidated figures for temperatures relative to pre-industrial, WMO calculates anomalies relative to 1981-2010 for each dataset and then adds an offset of 0.69°C, which is the difference between 1981-2010 and 1850-1900 as estimated by IPCC. The uncertainty in the offset is 0.12°C. The anomalies from the constituent datasets are then averaged to get a single value for the year. The spread of the datasets is combined with the uncertainty in the offset to get a combined uncertainty of 0.13°C. This method was used in the State of the Global Climate 2023 and 2024 and adapted to the eight datasets used in 2025. The description can be found in this link.