The WMO has confirmed that 2025 has become one of the three warmest years on record, continuing the trend of abnormally high temperatures. The last 11 years have been the warmest on record, and ocean warming continues to intensify.
Key Messages
- The last 11 years have been the warmest on record.
- The short-term cooling caused by the La Niña phenomenon will not change the overall warming trend.
- Ocean temperatures continue to rise at the same intensity.
- The WMO combines eight different datasets to form a single authoritative source of information.
- International data exchange is essential for climate monitoring.
According to the analysis of eight datasets conducted by the WMO, the average global temperature in 2025 was 1.44 °C (with a margin of uncertainty of ± 0.13 °C) above the average level for 1850–1900. In two datasets, 2025 ranked second among the warmest years, while in six others, it ranked third.
The last three years (2023–2025) have been the warmest across all eight datasets. The average temperature during this period was 1.48 °C (with a margin of uncertainty of ± 0.13 °C) above pre-industrial levels. From 2015 to 2025, the 11 warmest years in history were recorded.
WMO Secretary-General Celeste Saulo noted: “Although 2025 began and ended with the cooling La Niña phenomenon, it still became one of the warmest years due to the accumulation of greenhouse gases in the atmosphere. This led to extreme weather conditions, including heatwaves, heavy rainfall, and powerful tropical cyclones, highlighting the need for effective warning systems.”
“Monitoring the climate situation, carried out by the WMO using comprehensive and scientifically grounded data collection, is crucial as it is necessary to ensure the availability and reliability of information about the state of the Earth,” Saulo added.
The WMO statement was released in connection with the publication of global temperature reports from various data providers.
Among them are the Copernicus Climate Change Service, the Japan Meteorological Agency, NASA, the National Oceanic and Atmospheric Administration (NOAA) of the USA, and others. This year, the WMO included two additional datasets for the first time: a dynamically consistent temperature dataset and a combined surface temperature dataset from China.
Six of these datasets are based on measurements taken at weather stations, ships, and buoys using statistical methods to fill in gaps. Two datasets are reanalyses that combine past observations, including satellite data, with models to create consistent time series. All key datasets use different methodologies, leading to variations in temperature readings.
According to DCENT and GISTEMP, 2025 ranked second among the warmest years, while according to the other six datasets, it ranked third.
The actual average global temperature in 2025 was 15.08 °C; however, the uncertainty in this estimate is significantly higher than that regarding the temperature anomaly for the year.
The WMO is a UN agency dealing with weather, climate, and water resources, striving to provide reliable analysis to support decision-making.
Ocean Temperature
A separate study published in the journal Advances in Atmospheric Sciences showed that ocean temperatures in 2025 were also among the highest on record, indicating heat accumulation in the climate system.
About 90% of the excess heat caused by global warming is stored in the ocean, making it a critically important indicator of climate change. The study, led by Lizhin Chen from the Institute of Atmospheric Physics in China, found that in 2025, the global ocean heat content in the upper 2000-meter layer increased by 23 ± 8 zettajoules compared to 2024, which is 200 times the total global electricity production in 2024.
Regionally, about 33% of the world's oceans recorded some of the highest temperatures in history, and about 57% fell into the top five warmest areas, including the tropics, southern Atlantic, Mediterranean Sea, northern Indian Ocean, and Southern Ocean, further emphasizing global warming.
The study also showed that the annual average sea surface temperature in 2025 was 0.49 °C above the baseline level of 1981–2010 and 0.12 ± 0.03 °C lower than in 2024, which is related to La Niña conditions, although 2025 still ranks third among the warmest years.
Notes for Editors
The WMO will present a full description of key climate change indicators, including greenhouse gas levels, surface temperature, ocean heat content, sea level, glacier retreat, and sea ice extent, in its Statement on the State of the Global Climate for 2025, which will be released in March 2026. This report will also contain information on significant climate events.
The datasets used by the WMO provide nearly complete coverage of near-surface measurements, including statistical methods to fill data gaps in low-coverage regions such as polar areas. Reanalyses also provide a global analysis by combining past data, including satellite observations, with models to create time series of climate variables.
To calculate the aggregated temperature data relative to pre-industrial levels, the WMO uses anomalies relative to 1981–2010 for each dataset and adds a shift of 0.69 °C—the difference between the periods 1981–2010 and 1850–1900 according to estimates from the IPCC. The uncertainty in the shift is 0.12 °C. Anomalies from the datasets are averaged to obtain a single annual value, and the spread of the data is combined with the uncertainty of the shift to determine the overall uncertainty of 0.13 °C. This method was used in previous climate state reports for 2023 and 2024 and has been adapted for the eight datasets applied in 2025. Details can be found at the link.
