Surface air temperature for May 2023

Temperatures for May 2023 were not far from their 1991-2020 climatological average over most of Europe. The month was a little warmer than normal over the west of the continent and a little cooler than normal over central and eastern parts. It was substantially above normal only over the far north-east of the continent.

Canada and the northern USA experienced a very warm month, with temperatures reaching more than 10°C above average west of Hudson Bay. Numerous high-temperature records were broken and there were record wildfire emissions from British Columbia in the west to Nova Scotia in the east. Africa saw unusually high temperatures over South Sudan and the Central African Republic, and to the south over countries that included Botswana, Zambia and Zimbabwe. Several countries in South-East Asia experienced either their warmest ever recorded day or their warmest May day. The month was also warmer than usual over much of South America.

Conversely, May 2023 was a relatively cold month over Australia, where the country’s average daily-minimum temperature was the lowest since 1944. North-West India had its 8th coldest average temperature in a record dating back to 1901. Temperatures were also well below average over a region to the north of India extending to Mongolia and southern Siberia, and over much of the Antarctic Plateau and Ross Ice Shelf.

Above-average air temperatures predominated over the oceans. El Niño conditions continued to develop over the equatorial eastern Pacific. Air temperatures were unusually high over the Weddell Sea and eastward around the Antarctic coast to the Ross Sea, with regions of relatively mild temperature extending northward over much of the southern Atlantic, Indian and Pacific Oceans. Air temperatures were higher than the 1991-2020 average throughout the tropics and over most of the North Pacific and North Atlantic, especially west of Europe and North Africa. Temperatures were lower than normal over the Arctic Ocean. Averages over all ice-free seas of both sea-surface and air temperature are higher for May 2023 than for any other May in the data record.

Globally, May 2023 was:

• 0.40°C warmer than the 1991-2020 average for May
• the joint second warmest May in this data record
• about 0.07°C cooler than May 2020, the warmest May on record
• similar in temperature (within 0.02°C) to the Mays of 2016 and 2017.

European-average temperature anomalies are generally larger and more variable than global anomalies. The European-average temperature for May 2023 was nevertheless almost the same as the 1991-2020 average. The month was about 2.1°C cooler over Europe than May 2018, the warmest May in the record.

Temperatures for the boreal spring of 2023 were predominantly above the 1991-2020 average for the south west and far east of Europe. They were below average over parts of Norway and Sweden, and to a lesser extent over central and south-eastern Europe.

Seasonal average temperatures were much above average over north-eastern Canada, western Asia apart from the Middle East, eastern Asia, several parts of Africa, southern South America and East Antarctica. The season was appreciably colder than average over the western USA, including Alaska, and south central Canada, a region extending northward from central India, northern Australia and West Antarctica.

The seasonal-average temperatures over sea were similar in their pattern of differences from the 1991-2020 average to that seen for May 2023.

The seasonal average temperature for Europe from March to May 2023 was 0.36°C above the 1991-2020 climatological average for the season. Although the spring of 2023 was warmer than the previous three springs, twelve years from 1989 onwards had warmer springs than 2023, for Europe as a whole.

Temperatures averaged over the last 12 months were:

• above the 1991-2020 average over much of the globe
• well above average over most of Europe
• well above average also over eastern and northern North America, Greenland, north-western Africa, western and parts of eastern Asia, and parts of East Antarctica
• also above average over seas around Antarctica and in the European sector of the Arctic, and over much of the North Pacific, part of the South Pacific, the Atlantic and southern Indian Ocean
• below average over the eastern equatorial Pacific, where the La Niña event that peaked in late 2020 reintensified later in 2021 and continued through 2022 into the start of 2023
• below average over several other oceanic areas, including a large part of the southern Pacific and the western Indian Ocean
• below average over Australia and West Antarctica, and to a lesser extent over several other land areas.

There is more variability in average European temperatures, but relatively dense observational coverage of the continent reduces uncertainty. The average for this latest twelve-month period is 1.0°C above the 1991-2020 average. 2020 is the warmest calendar year on record for Europe by a clear margin, with a temperature of 1.2°C above the 1991-2020 average.

Note on global values from ERA5 and other temperature datasets

There is general agreement among datasets that the period since 2015 is much warmer globally than any previous period. There is also agreement that global temperature has risen at an average rate close to 0.2°C per decade since the late 1970s. There is nevertheless still some spread between the datasets for recent years, such as for 2020 and 2021, and the annual average temperature anomalies for these years from ERA5 are generally higher than those from the five other datasets considered. The differences range from 0.01 to 0.07°C for 2016-2022. The range is 0.00 to 0.06°C if air temperature over sea is replaced by sea-surface temperature for ERA5 and the other dataset for which sea-surface temperature was not used by design. The remaining differences depend partly on the extent to which datasets represent the relatively warm conditions that have predominated over the Arctic and Antarctic during these years. Differences elsewhere in estimates of sea-surface temperature and surface air temperature over land have been further factors.

The surface air temperature analysis homepage explains more about the production and reliability of the values presented here, but has yet to be updated to include the new information on dataset spread mentioned above.

Read more about long-term temperature changes for the globe, the Arctic and Europe in the Temperature indicator.