The global temperatures in May were the second-warmest in the past three decades as polar ice continues to melt, according to a monthly report by Europe’s Earth observation agency Copernicus.

The area covered by sea ice in Antarctica last month touched a new low — third time to happen this year — and was 17% below average for the period between 1979 and 2023. It also coincided with unprecedented temperatures over all oceans that aren’t covered by ice, the report said.

“We are seeing the El Niño signal continuing to emerge in the equatorial Pacific,” said Samantha Burgess, deputy director of the Copernicus Climate Change Service. “The average temperature over all ice-free seas for May 2023 was higher than for any other May.”

El Niño is a weather-changing event that’s driven by anomalies in ocean water temperatures. It disrupts wind and rainfall patterns, as well as changes ocean and land temperatures across the planet. Forecasters see growing odds that El Niño emerges in coming months, peaking around December or January. Read More: El Nino Promises to Upend Weather, Bringing Floods and Drought

In southern Europe, May was wetter than the average between 1991 and 2020, with heavy rains leading to floods in Italy and the western Balkans. Still, drier-than-average conditions were recorded over most of the Iberian Peninsula, as well as Denmark, the Baltic countries, southern Scandinavia and much of western Russia.

Elsewhere, the month was drier than average over large regions of North America, the Horn of Africa, southern Africa, South America, Australia and east and southeast Asia. Parts of Canada, Africa and southeast Asia were significantly warmer than average. Read More: One in Three People Will Live in Dangerously Hot Areas by 2080