The EU’s Copernicus Climate Change Service is warning that “exceptional temperature anomalies” in October mean 2023 is “virtually certain” to be warmest year on record.

Globally averaged surface air temperature anomalies relative to 1991–2020

for each October from 1940 to 2023. Data Source: ERA5. Credit: C3S/ECMWF.

October 2023 was the warmest October on record globally, with an average surface air temperature of 15.30°C, 0.85°C above the 1991-2020 average for October and 0.40°C above the previous warmest October, in 2019.

Implemented by the European Centre for Medium-Range Weather Forecasts on behalf of the European Commission with funding from the EU, Copernicus routinely publishes monthly climate bulletins reporting on the changes observed in global surface air and sea temperatures, sea ice cover and hydrological variables.

All the reported findings are based on computer-generated analyses and according to ERA5 dataset, using billions of measurements from satellites, ships, aircraft and weather stations around the world.

The global temperature anomaly for October 2023 was the second highest across all months in the ERA5 dataset, behind September 2023.

The month as a whole was 1.7°C warmer than an estimate of the October average for 1850-1900, the designated pre-industrial reference period.

For the calendar year to date, January to October, the global mean temperature for 2023 is the highest on record, 1.43°C above the 1850-1900 pre-industrial average, and 0.10°C higher than the ten-month average for 2016, currently the warmest calendar year on record.

For Europe, October 2023 was the fourth warmest October on record, 1.30°C higher than the 1991-2020 average.

The average sea surface temperature for October over 60°S–60°N was 20.79°C, the highest on record for October.

El Niño conditions continued to develop in the equatorial Pacific, although anomalies remain lower than those reached at this time of year during the development of the historically strong 1997 and 2015 events.

October 2023 – sea ice and rainfall highlights

October marked the sixth consecutive month that Antarctic sea ice extent remained at record low levels for the time of year, with a monthly value 11% below average.

In October 2023, precipitation was above average across most of Europe: Storm Babet hit northern Europe, and storm Aline impacted Portugal and Spain, bringing heavy precipitation and flooding.

Beyond Europe, it was wetter than average in several regions including: the southwest of North America, parts of the Arabian Peninsula, regions of Central Asia and Siberia, southeast China, Brazil, New Zealand and regions of southern Africa. Such conditions were often associated with the transit of cyclones which triggered heavy rainfall and substantial damage.

It was drier than average in the southern USA and parts of Mexico both experiencing drought, in regions of central and easternmost Asia, and in most of the extratropical southern hemisphere, including Australia.

Sense of urgency for ambitious climate action has never been higher

Samantha Burgess, Deputy Director of the Copernicus Climate Change Service (C3S) commented:

"October 2023 has seen exceptional temperature anomalies, following on from four months of global temperature records being obliterated. We can say with near certainty that 2023 will be the warmest year on record, and is currently 1.43ºC above the preindustrial average. The sense of urgency for ambitious climate action going into COP28 has never been higher”.