After analyzing eight international data sets, the organization said global average surface temperatures last year were 1.44°C above the average from 1850 to 1900.
Two of these data sets ranked 2025 as the second warmest year in the 176-year record.and the other six ranked it as the third warmest year.
Warm despite La Niña
The fact that 2025 was slightly colder than the three-year average from 2023 is partly explained by the La Niña phenomenon, which is associated with colder climate.
But the WMO insisted that any temporary cooling caused by La Niña is not reversing the long-term trend of warmer temperatures.
“The year 2025 began and ended with a cooling of La Niña and yet It was still one of the warmest years on record globally due to the buildup of heat-trapping greenhouse gases. in our atmosphere,” said WMO Secretary-General Celeste Saulo.
The organization added that high temperatures on land and sea last year helped fuel extreme weather conditions, including heat waves, heavy rainfall and deadly tropical cyclones, underscoring the need for early warning systems.
Ocean heat
Citing a separate study, the WMO highlighted that Ocean temperatures were also among the highest on record last year.reflecting the long-term accumulation of heat within the climate system.
Regionally, about 33 percent of the global ocean surface was among the three warmest historical conditions (1958-2025), while about 57 percent was among the top five, including the southern and tropical Atlantic Ocean, the Mediterranean Sea, the northern Indian Ocean, and the Southern Oceans, highlighting widespread ocean warming in the basins.
The WMO will provide full details of key indicators of climate change, including greenhouse gases, surface temperatures, ocean heat and other trends, in its State of the Global Climate 2025 report, to be published in March.