October 2026 sets a new world heat record for this month of year. The average air temperature is 15.35 °C, according to the latest European climate assessment. It exceeds the estimated level of the pre-industrial period by 1.75 °C. This balance reinforces the likelihood that the total of 2026 will also pass the annual threshold of 1.5 °C.
The October balance sheet data put this month above the previous record, set in 2023. The difference is 0.90 °C compared to the October average for the period 1991-2020. August, September and October now constitute three consecutive months beyond 1.5 °C compared to 1850-1900.
A world record in heat, one year still unfinished
The statistical model of the European climate service estimates the probability of an annual exceedance of 1.5°C at over 99%. It gives about 80% chance to 2026 to become the second warmest year measured. The remaining 20% is for a year equal to or exceeding 2024.
This projection uses the data available until October. It remains separate from the final balance sheet, which will include November and December.
The Paris threshold is measured over time
A monthly or annual exceedance of 1.5°C alone does not amount to the sustainable crossing of the Paris Agreement objective. This concerns the evolution of the world average temperature over several decades. The difference is due to the measurement period used to assess this commitment.
The temperature of a month or year also varies with natural phenomena. El Niño and La Niña, as well as volcanic eruptions, may temporarily increase or mitigate observed values. These variations overlap with the underlying trend of human activities.
The Paris Agreement envisages containing the warming well below 2°C and continuing efforts to limit it to 1.5°C. The reading of annual surveys must therefore retain two benchmarks: their immediate level and their place in a longer evolution.
El Niño strengthens ocean heat
International weather forecasts broadcast on 8 October announced a strengthening of El Niño. They covered exceptionally high temperatures in the central and eastern tropical Pacific during the October-December quarter. This affects rain and temperature regimes, with consequences for ecosystems and economic activities.
The European monthly review confirms exceptional ocean heat. Outside the polar regions, the average sea surface temperature is 20.95 °C, a record for October. Europe also has its second hottest month of October in the European series of surveys.
The November and December surveys will now clarify the final ranking of 2026 and the extent of its gap in the pre-industrial period.
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