May 2026 was the world's second-warmest May on record, with Western Europe experiencing an unusually early heatwave, the European Union's climate monitoring service said on Wednesday.

The Copernicus Climate Change Service (C3S) said the global average surface air temperature in May 2026 was 15.81 degrees Celsius, 0.55 degrees Celsius above the 1991-2020 average. The reading was second only to May 2024 and 1.42 degrees Celsius above estimated pre-industrial levels.

Sea surface temperatures between 60 degrees south latitude and 60 degrees north latitude averaged 20.90 degrees Celsius, the second-highest on record for May, as the tropical Pacific continued its transition toward El Nino conditions expected to develop in the coming months.

Western Europe was hit by an early and intense heatwave in the second half of May, with France, Britain, Ireland, Spain and Portugal hitting multiple local temperature records. In some areas, "feels-like" temperatures reached 35 to 40 degrees Celsius.

"In Europe, an unusually early and intense heatwave 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.

The C3S said the continued warming trend, combined with persistently high ocean temperatures and emerging El Nino conditions, highlights growing risks of more frequent and intense climate extremes worldwide.