2025 began and ended with La Niña conditions, which generally cool down global average temperatures. Despite this, the year ended up as the third warmest year on record and the warmest La Niña year on record, according to Berkeley Earth’s Annual Temperature Report 2025.
La Niña is the cooler than normal phase of the El Niño Southern Oscillation (ENSO) phenomenon which occurs in the Equatorial Pacific Ocean and is generally responsible for different weather conditions in different regions of the world along with overall cooling down.
La Niña conditions emerged in the Equatorial Pacific Ocean in December 2024 and were around till March 2025. In April, ENSO neutral conditions were established in the region when neither the impacts of La Niña nor El Niño, which is the warmer than normal phase of ENSO, are experienced.
The Equatorial Pacific Ocean reverted back to La Niña conditions in September 2025 which are still prevalent but are rapidly collapsing and the scenario is possibly moving towards an El Niño in summer 2026. Even with many months of La Niña conditions, the global average annual temperature anomaly was 1.44°C, the third highest on record after 2024 and 2023.
The report also highlighted that during 2025, 9.1 per cent of Earth’s surface experienced its highest annual average temperature. Of this, 10.6 per cent of land areas suffered from record breaking warmth in 2025 while 8.3 per cent of ocean areas were hottest on record. The record heat was over major population centres, according to the report.
“Roughly 770 million people (8.5% of the global population) experienced record warm annual temperatures, primarily in Asia, while no regions recorded a record cold year,” according to a press statement issued by Berkeley Earth.
Similar to the Copernicus Climate Change Service (C3S), Berkeley Earth also found that “the last 11 years have included all 11 of the warmest years observed in the instrumental record, with the last 3 years including all of the top 3 warmest.”
“The warming spike in 2023 to 2025 suggests that the past warming rate is no longer a reliable predictor of the future, and additional factors have created conditions for faster warming, at least in the short-term,” according to the statement.