The Copernicus Climate Change Service, operated by the European Centre for Medium-Range Weather Forecasts on behalf of the European Commission, has ranked 2025 as the third warmest year in its records. In its Global Climate Highlights 2025 report, published in January 2026, Copernicus said the global average surface air temperature for the year was 14.97°C, which is 1.47°C above the 1850 to 1900 pre-industrial level.
2025 was 0.01°C cooler than 2023 and 0.13°C cooler than 2024, the warmest year on record. January 2025 was the warmest January in the dataset, and March, April and May were each the second warmest for their respective months. European temperatures in 2025 also ranked among the highest on record, according to a summary published by the European Commission.
Why 2025 stayed close to the record
2024 was boosted by an El Niño event, a natural pattern in the tropical Pacific that releases heat from the ocean to the atmosphere. El Niño faded in 2024, and weak La Niña conditions developed at times during 2025. La Niña years are usually cooler than El Niño years. The fact that 2025 came close to 2023 and 2024 despite the absence of El Niño is one reason scientists at Copernicus pointed to the underlying warming trend.
Copernicus also noted that the three-year average for 2023 to 2025 exceeded 1.5°C above pre-industrial levels for the first time. The Paris Agreement goal of limiting warming to 1.5°C refers to long-term averages over about 20 years, so a single year or a three-year window above that level does not mean the goal has been formally breached. It does show how close the climate system is to that threshold.
What the temperature record means for energy
Temperature is one of the main drivers of energy demand. Cold winters raise demand for gas and electricity for heating, and hot summers raise electricity demand for cooling. Energy companies, grid operators and traders build weather normals into demand forecasts, typically based on averages over the past 10, 20 or 30 years. In a warming climate, those averages lag behind actual conditions.
In Europe, the effect cuts both ways. Milder winters reduce gas demand for heating, which has helped lower consumption in recent years alongside efficiency gains and higher prices after 2022. Hotter summers increase air conditioning use, particularly in southern Europe, and raise peak electricity demand in months when solar output is high but wind output is often low. In the United States, India and the Middle East, summer peaks are already the main constraint on power systems.
Supply-side effects
Higher temperatures also affect supply. Thermal and nuclear power plants that draw cooling water from rivers face output limits when river temperatures rise, as happened in Switzerland and France during the summer of 2025. Transmission lines carry less power when air temperatures are high. Hydropower output depends on rainfall and snowmelt, which are shifting with the climate. Solar panels become slightly less efficient at high temperatures, although high solar output during heat waves often offsets that.
Ocean heat and extreme events
Copernicus reported that sea surface temperatures remained exceptionally high in 2025, though below the record of 2024. Warm oceans supply energy to tropical cyclones and raise the risk of intense rainfall. Hurricane Melissa, which struck Jamaica in October 2025 as a Category 5 storm, crossed waters that were unusually warm. Extreme events affect energy infrastructure directly, through damage to power lines and ports, and indirectly, through insurance costs and investment risk.
How the data are produced
The Copernicus figures are based on the ERA5 reanalysis, which combines billions of observations from satellites, weather stations, ships and aircraft with a weather forecasting model to produce a consistent record of the global climate. Other datasets, including those from NASA, the US National Oceanic and Atmospheric Administration, the UK Met Office and Berkeley Earth, produce slightly different rankings and values because of differences in methods and coverage. The WMO, the UN weather agency, combines several datasets in its annual State of the Global Climate report.
Market relevance
For gas and power markets, the temperature record is part of a longer trend that affects seasonal planning, storage strategy and capacity procurement. European gas storage targets, for example, are set with an eye to winter demand, and milder winters reduce the risk of shortages. Capacity markets in the United States, such as those run by PJM, increasingly model summer and winter peaks under hotter and more variable conditions. Utilities in fast-growing markets must plan for both rising cooling demand and new loads from data centres.
Heating and cooling degree days
Energy analysts translate temperature data into heating degree days and cooling degree days, which measure how far daily temperatures fall below or rise above a comfort baseline. These metrics feed directly into gas and power demand models. A long-term decline in heating degree days in Europe and North America reduces winter demand per household, while rising cooling degree days increase summer demand. The balance between the two varies by region. Northern Europe still has far more heating demand than cooling demand, while the southern United States, the Gulf states and South Asia are dominated by cooling.
The shift has commercial consequences. Gas utilities that sell mainly in winter see lower volumes in mild years. Power generators with flexible plants can earn more during summer peaks. Grid operators must plan reserve margins for hotter summer peaks while also keeping enough capacity for cold snaps, which still occur and can be severe even in a warming climate.
Planning assumptions
Regulators and system operators have started to replace simple historical averages with forward-looking climate scenarios in their planning studies. European transmission system operators use climate projections in adequacy assessments, and several US grid operators have added extreme heat and cold scenarios to resource adequacy studies. The annual temperature record provides a reference point for testing whether those scenarios are realistic.
What to watch
The next milestones are the WMO State of the Global Climate report, expected in March, and seasonal forecasts for the northern hemisphere summer. Forecasters are watching the tropical Pacific for signs of a return to El Niño later in 2026, which would increase the likelihood of new temperature records.