According to WMO data, 2025 became one of the warmest years in recorded history, continuing a streak of abnormal temperatures. The last 11 years have been the warmest, and ocean temperatures continue to rise.
Key Messages
- The last 11 years have been the warmest in recorded history
- The temporary cooling caused by the La Niña phenomenon will not change the long-term trend
- Ocean temperatures continue to rise at the same rate
- The WMO combines eight datasets, creating a single authoritative source of information
- International data exchange serves as the basis for climate monitoring
According to a combined analysis of eight datasets conducted by the WMO, the average ground temperature on the planet in 2025 exceeded the average values of 1850-1900 by 1.44 °C (with a margin of uncertainty of ± 0.13 °C). In two datasets, 2025 ranks second among the warmest years in 176 years of observations, while in the other six, it ranks third.
The last three years (2023-2025) have been the warmest in the history of all eight datasets. The average temperature for this triple period was 1.48 °C (with a margin of uncertainty of ± 0.13 °C) above pre-industrial levels. From 2015 to 2025, all 11 years made the list of the warmest across all eight datasets.
The WMO Secretary-General, Celeste Saulo, noted: “Although 2025 began and ended with La Niña cooling, it still turned out to be one of the warmest years due to the accumulation of greenhouse gases in the atmosphere. This led to high temperature levels on land and in the ocean, contributing to extreme weather events such as heatwaves and heavy rainfall, highlighting the importance of early warning systems.”
She also added that “climate monitoring conducted by the WMO using collaborative and scientifically based data is more important than ever, as it is essential to ensure access to reliable information about the state of the Earth for everyone.”
This WMO statement was made as part of the publication of global temperature data from various providers, including:
The Copernicus Climate Change Service of the European Centre for Medium-Range Weather Forecasts (ERA5), the Japan Meteorological Agency (JRA-3Q), NASA (GISTEMP v4), the National Oceanic and Atmospheric Administration of the USA (NOAAGlobalTemp), the UK Met Office in collaboration with the Climate Research Unit at the University of East Anglia (HadCRUT.5.1.0.0), and Berkeley Earth (USA). This year, the WMO also considered two additional datasets: a dynamically consistent temperature dataset (DCENT/UK, USA) and a combined surface temperature dataset for China (CMST).
Six of these datasets are based on measurements from weather stations and ships, using statistical methods to fill in gaps in data. Two datasets (ERA5 and JRA-3Q) are reanalyses that combine previous observations, including satellite data, with models to create consistent time series for various climate variables, including temperature. All key datasets use different methodologies, leading to differences in temperature readings and annual rankings.
2025 was the second warmest year according to DCENT and GISTEMP, and third according to the remaining six datasets (Berkeley Earth, CMST, ERA5, HadCRUT5, JRA-3Q, and NOAAGlobalTemp).
The average global temperature in 2025 was estimated at 15.08 °C, however, there is significant uncertainty regarding the actual temperature, around 0.5 °C, compared to the temperature anomaly for that year.
The WMO, as a UN agency dealing with weather, climate, and water issues, aims to provide authoritative analysis to support decision-making.
Ocean Temperature
In a new study published in the journal Advances in Atmospheric Sciences, it is stated that ocean temperatures in 2025 also reached record levels, reflecting the long-term accumulation of heat in the climate system.
About 90% of the excess heat caused by global warming is stored in the oceans, making ocean heat content an important indicator of climate change. The study, led by Lizhin Chen from the Institute of Atmospheric Physics of the Chinese Academy of Sciences, showed that from 2024 to 2025, global ocean heat content in the upper 2000-meter layer increased by ∼23 ± 8 zettajoules compared to 2024, which is approximately 200 times the global electricity production in 2024.
Regionally, about 33% of the area of the World Ocean was among the top three warmest on record (1958-2025), and 57% was among the top five warmest, including the tropics, the southern Atlantic Ocean, the Mediterranean Sea, the northern Indian Ocean, and the Southern Ocean, highlighting global warming across various ocean basins.
The study also showed that the global average sea surface temperature in 2025 was 0.49 °C above the baseline of 1981-2010 and (0.12 ± 0.03) °C lower than in 2024, which aligns with La Niña conditions, yet still ranks as the third warmest year in recorded history.
Notes for Editors
The WMO will present comprehensive information on key climate indicators, including greenhouse gas concentrations, surface temperature, ocean heat content, sea level rise, glacier retreat, and sea ice extent, in its Statement on the State of the Global Climate in 2025, which will be published in March 2026. This document will also provide information on phenomena with significant impacts.
The datasets used by the WMO provide nearly complete coverage of near-surface measurements, applying statistical methods to fill in gaps in areas with insufficient data coverage, such as polar regions. Reanalyses offer a comprehensive global analysis, combining past observations with models to create consistent time series for many climate variables, including temperature across all regions.
To calculate summary temperature data relative to pre-industrial levels, the WMO computes anomalies based on data from 1981-2010 for each dataset and adds a shift of 0.69 °C, which is the difference between the periods 1981-2010 and 1850-1900 according to IPCC estimates. The uncertainty in this shift is 0.12 °C. Anomalies from different datasets are averaged to produce a single annual figure. The spread between datasets is combined with the uncertainty in the shift to obtain an overall uncertainty of 0.13 °C. This method was used in the reports on the state of the global climate in 2023 and 2024 and adapted to the eight datasets used in 2025. More detailed information is available at the link.
