World had warmest October on record

08 November 2023

The monthly global temperature record was once again smashed in October, continuing an extended streak of extraordinary land and ocean surface temperatures and low sea ice, according to the European Union’s Copernicus Climate Change Service (C3S). October was the fifth month in a row of record-warm global temperatures.

This means that 2023 is almost certain to be the warmest year on record. WMO will confirm this in its provisional State of the Global Climate 2023 report, which will be released on 30 November on the opening day of the UN Climate Change conference, COP28.

In order to provide a longer-term perspective for decision-makers at COP28, WMO will also issue a State of the Global Climate 2011-2020 decadal report. Its annual report on the drivers of climate change – greenhouse gas concentrations from human activities – will be released on 15 November.

Graph global surface air temperature
Global Surface Air Temperature Anomalies - October 2023

WMO uses several international datasets for its State of the Global Climate reports, including the ERA5 reanalysis dataset of the Copernicus Climate Change Service,  implemented by the European Centre for Medium-Range Weather Forecasts.

It was by far the warmest October on record, 0.85°C above the 1991-2020 average, and 0.40°C above the previous warmest October. The global temperature anomaly was the second highest across all months in the ERA5 dataset, behind September 2023, it said.

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, it said.

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

Daily sea surface temperature
Graph on Daily sea surface temperature

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. Arctic sea ice extent reached its 7th lowest value for October, at 12% below average.

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.

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.