Last month ranked as the world's second-warmest May on record, showing how quickly climate extremes have become "the new normal", the European Union's climate monitoring service said.

Western Europe was hit by an early and intense heat wave in May that shattered multiple national records and left people, crops, and ecosystems little time to adapt, according to the Copernicus Climate Change Service.

The monitor said the May global average surface air temperature was 15.81 C, which was 0.55 C above the 1991-2020 average. The reading was second only to May 2024 and was 1.42 C above estimated pre-industrial, or 1850-1900, levels.

France, Ireland, Portugal, and the United Kingdom experienced particularly severe conditions, while Spain had 101 heat-related deaths, the highest for the month since monitoring began.

France and the UK saw a rise in drowning incidents as people sought relief in unfamiliar waters. In some areas, "feels-like" temperatures reached 35 to 40 C.

In its monthly report released on Wednesday, the monitoring service said: "While remarkable, the event is consistent with Europe's rapid warming and the long-term trend toward more frequent, more intense and earlier-season heat waves."

It said there was a rapid transition from colder-than-average to warmer-than-average conditions around May 20 over much of the continent, followed by an intense heat wave in the second half of the month.

The report said the speed of the temperature swing likely increased impacts on populations, leaving little time for people to acclimatize.

"In Europe, an unusually early and intense heat wave demonstrates how quickly climate extremes are becoming the new normal rather than the exception," said Samantha Burgess, strategic lead for climate at the European Centre for Medium-Range Weather Forecasts, which operates the Copernicus service.

Across the continent, there was a contrast in precipitation, with much of western, central, and eastern Europe experiencing drier-than-average conditions, while parts of Bulgaria, Moldova, and Turkiye were hit by severe flooding.

The report said that globally, May extended a run of near-record air and ocean temperatures, and noted unusually high sea surface temperatures in the tropical Pacific, with conditions moving toward an El Nino phase — a periodic warming of the tropical Pacific that can intensify global weather extremes.

Beyond Europe, wetter-than-average conditions were observed in parts of northern and southeastern North America, areas of Asia north of the Indian subcontinent, western China, parts of Brazil, southern Africa, and much of Australia.

By contrast, drier-than-average conditions prevailed in much of South America, large parts of Central Asia, southwestern Australia, Madagascar, and the central United States.