2025 ‘almost certain’ to be one of the three hottest years on record

The year 2025 is almost certain to rank as one of the three hottest years on record, according to an analysis released Thursday by the Copernicus Climate Change Service, the European Union’s satellite monitoring system.

The forecast follows the global temperature analysis for October, which was the third-hottest October globally ever recorded, with an average temperature of 15.14C (59F).

The reading was 0.70C (1.26F) higher than the 1991–2020 average. Last month’s global average temperature was also 1.55C (2.79F) higher than the pre-industrial average (1850–1900). This marks the first time since April that the global temperature anomaly in a single month exceeded 1.5C above pre-industrial levels.

However, October 2025 was 0.16C (0.29F) cooler than the record-breaking October of 2023, which remains the hottest October ever recorded.

1.5C threshold under threat

The sustained temperature anomalies indicate a significant, long-term climate shift. The 12-month period from November 2024 to October 2025 showed an average temperature 0.62C (1.12F) above the 1991–2020 average and 1.5C (2.7F) above pre-industrial levels.

Following these readings, it is now almost certain that 2025 will rank as the second- or third-hottest year on record, expected to be at or just below the temperature level of 2023. The year 2024 remains the hottest year ever recorded.

Furthermore, projections suggest the three-year period from 2023–2025 will surpass the 1.5C threshold, even if the average rise in 2025 does not exceed it. This would be the first time in recorded history that a three-year average has reached such a high level.

The findings echo a warning issued last week by the UN Environment Programme (UNEP), which cautioned that the global multi-year average temperature is at risk of exceeding the 1.5C threshold within the next decade, challenging the commitments under the Paris Agreement.