Warmest October on record globally as El Niño strengthens

Last month was the warmest October on record globally and the third consecutive month to exceed 1.5°C above pre-industrial levels. One of the drivers of this abnormal warmth was a strengthening El Niño causing exceptionally high temperature anomalies in the tropical Pacific Ocean.

According to data from the European Union's Copernicus Climate Change Service (C3S), the average global surface air temperature in October 2026 was 1.75°C above the pre-industrial average. This was the highest October anomaly on record and the third consecutive month above the +1.5°C threshold.

Sea surface temperature anomalies in October 2026
Image: Monthly global surface air temperature anomalies from 1940 to 2026, relative to the 1850–1900 baseline). Source: ECMWF Copernicus C3S / ERA5.

Sea surface temperatures also set a record for warmth in October 2026, averaging 20.95°C for the planet’s oceans outside the polar regions. This beat the previous October record of 20.79°C from 2023, which was also an El Niño year.

Water temperatures in the central and eastern tropical Pacific Ocean were exceptionally warm in October due to the strengthening El Niño. The monthly average sea surface temperature in the Niño 3.4 region reached an all-time high of 29.94°C, a remarkable 3.21°C above average.

Image: Global sea surface temperature anomalies in October 2026. Source: ECMWF C3S / ERA5.

While water temperatures were cooler-than-average over parts of the southern and western Pacific Ocean in October – also a consequence of El Niño – there were also some large positive temperature anomalies near Australia. According to the Bureau of Meteorology, sea surface temperatures set new October records for warmth in the Tasman Sea and the water surrounding southern Australia.

Image: Sea surface temperature anomalies near Australia in October 2026. Source: Bureau of Meteorology.

With October’s record-breaking warmth and El Niño still gaining strength in the tropical Pacific Ocean, this year is on track to be one of the warmest in recorded history based on global temperatures. Based on CS3 projections, 2026 will most likely be the second warmest year on record and should have a global air temperature anomaly somewhere between 1.56°C to 1.61°C. This would make 2026 only the second year alongside 2024 to exceed 1.5°C above pre-industrial levels.