Copernicus: Third-warmest September on record amid persistently high ocean temperature

Bonn, 09/10/2025

Global Temperatures

September 2025 was the third-warmest September globally, with an average ERA5 surface air temperature of 16.11°C, 0.66°C above the 1991-2020 average for September.
September 2025 was 0.27°C cooler than the warmest September on record, in 2023, and only 0.07°C cooler than September 2024.
September 2025 was 1.47°C above the estimated 1850-1900 average used to define the pre-industrial level.
The 12-month average temperature from October 2024 to September 2025 was 0.63°C above the 1991-2020 average, and 1.51°C above the pre-industrial level.

Temperature in Europe and other regions

The average temperature over European land for September 2025 was 15.95°C, 1.23°C above the 1991-2020 average for September, ranking fifth highest on record for the month. This was only marginally different (within 0.04°C) from the fourth warmest in 2018 and the sixth warmest in 2011.
The most pronounced above-average air temperatures were recorded over Fennoscandia and eastern Europe.
Cooler-than-average temperatures were seen only over parts of western Europe and were typically less than one degree cooler than average.
Outside Europe, temperatures were most above average over Canada, parts of Greenland, northwesternmost Siberia and adjacent coastal regions, as well as large parts of Antarctica.
The only large regions globally with pronounced negative temperature anomalies were northern central Siberia, western Australia and parts of eastern Antarctica.

Sea surface temperature

The global average sea surface temperature (SST) for September 2025 was 20.72°C, the third-highest value on record for the month, 0.20°C below the September 2023 record.
Most of the North Pacific continued to experience much above-average SSTs, with record highs in some areas. In contrast, SSTs were close to or below the 1991-2020 average in the central and eastern equatorial Pacific, reflecting the ENSO-neutral conditions.
Around Europe, much-above average to record-high SSTs were experienced in a large region from the Norwegian Sea to the Kara Sea; in the Mediterranean, SSTs were mostly much-above average, especially in the western and central parts of the basin.
In the Arctic, the daily sea ice extent reached its 14th-lowest annual minimum in the satellite record, while the monthly extent ranked 13th lowest, at 12% below average, well above the record low of -32% observed in September 2012.
Regionally, below-average sea ice concentrations were most pronounced north of Svalbard and Franz Josef Land and in the Beaufort Sea.
Around Antarctica, the daily sea ice extent reached its third-lowest annual maximum, while the monthly extent ranked fourth lowest, at about 5% below average, behind 2023 (–9%) and 2024 (–7%).
Below-average sea ice concentrations around Antarctica were most pronounced in the Bellingshausen Sea and in the Indian Ocean sector while near- or above-average concentrations prevailed elsewhere.
In September 2025, it was wetter than average in northwestern and central Europe, Fennoscandia, along the eastern Black Sea coast, and in parts of Italy and coastal regions of Croatia and eastern Spain. In some cases, heavy rainfall caused flooding and associated disruptions.
Most of the Iberian Peninsula, the Norwegian coast, much of peninsular Italy, the Balkans, as well as parts of Ukraine and western Russia, were drier than average.
Beyond Europe, wetter-than-average conditions were experienced in the southwestern and central USA, Alaska northwestern Mexico and in regions of Brazil, Argentina and Chile. It was also wetter than average in the Northern Horn of Africa, the southern Arabian Peninsula, Pakistan and northwestern India, central Asia, eastern China. In many of these regions heavy precipitation led to flooding, often associated with the transit of tropical cyclones.
It was drier than average in parts of Canada, eastern USA and northeastern Mexico, in northern and easternmost Russia, north of the Indian subcontinent, as well as in Uruguay and part of Brazil.

More information about climate variables in September and climate updates of previous months as well as high-resolution graphics can be downloadedhere.

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