2025 Among Three Warmest Years Ever Recorded Despite La Niña Cooling, WMO Confirms

“The year 2025 both began and ended with a cooling La Niña, yet it was still one of the warmest years ever recorded,” said WMO Secretary-General Celeste Saulo.

 

The World Meteorological Organization (WMO) has confirmed that 2025 was one of the three warmest years on record, extending an unprecedented streak in which the past 11 years (2015–2025) have been the 11 warmest globally.

The findings underscore the strength of long-term global warming, showing that even a cooling La Niña phase was unable to offset the accumulated heat trapped by greenhouse gases—particularly in the oceans.

According to WMO’s consolidated analysis of eight global temperature datasets, the global average surface temperature in 2025 was 1.44°C (±0.13°C) above the 1850–1900 pre-industrial average. Two datasets ranked 2025 as the second-warmest year, while the remaining six placed it third.

The three-year period from 2023 to 2025 is the warmest such period on record in all datasets, with a consolidated average of 1.48°C above pre-industrial levels.

“The year 2025 both began and ended with a cooling La Niña, yet it was still one of the warmest years ever recorded,” said WMO Secretary-General Celeste Saulo. “This reflects the relentless accumulation of heat-trapping greenhouse gases. High land and ocean temperatures helped fuel extreme weather—heatwaves, heavy rainfall and intense tropical cyclones—highlighting the urgent need for early warning systems.”

Authoritative Climate Monitoring

WMO’s assessment brings together data from:

• ERA5 (Copernicus Climate Change Service)

• JRA-3Q (Japan Meteorological Agency)

• GISTEMP v4 (NASA)

• NOAAGlobalTemp v6 (United States)

• HadCRUT5 (UK Met Office & University of East Anglia)

• Berkeley Earth

• DCENT (UK/USA) – newly included

• CMST (China) – newly included

Six datasets rely primarily on direct observations from weather stations, ships and buoys, while two combine observations and models through reanalysis. Differences in methodology explain small variations in rankings and figures.

“Collaborative, scientifically rigorous climate monitoring is more important than ever,” Saulo said. “Earth information must be authoritative, accessible and actionable for decision-makers worldwide.”

Oceans Absorbing the Heat

A separate study published in Advances in Atmospheric Sciences confirms that ocean warming continued at near-record levels in 2025, reflecting the long-term energy imbalance in the climate system.

Around 90% of excess heat from global warming is stored in the ocean, making ocean heat content a critical climate indicator. From 2024 to 2025, the upper 2,000 metres of the global ocean absorbed about 23 ± 8 zettajoules of heat—roughly 200 times the world’s total electricity generation in 2024.

Regionally:

• 33% of the global ocean ranked among its three warmest years on record

• 57% ranked among the top five warmest, including the Mediterranean, North Indian Ocean, South Atlantic and Southern Oceans

Global average sea surface temperature in 2025 was 0.49°C above the 1981–2010 baseline. Although slightly cooler than 2024 due to La Niña, it still ranked as the third-warmest year on record.

Long-Term Trend Unmistakable

WMO emphasized that short-term climate variability such as La Niña does not reverse the long-term warming trend driven by human activity. The continued rise in land and ocean temperatures is intensifying climate impacts worldwide, with profound implications for ecosystems, water resources, food security and human safety.

The organization said the findings reinforce the need for accelerated climate action, sustained investment in global observation systems, and expanded early warning services to protect lives and livelihoods.