A brief burst of early-season heat in northern Japan set a new national maximum temperature record for the month of May on Sunday.

A warm air mass drifting over the country's Hokkaido prefecture during the weekend saw the mercury push into the high thirties. This is unusual for May, with the country typically experiencing its highest temperatures a couple of months later in the height of summer.

A weather station at Saroma, near Abashiri, reached a sweltering 39.5 degrees on Sunday afternoon. This was the highest temperature on record for any month in Hokkaido prefecture. It was also a new national temperature record for May.

Other sites in northern Japan exceeded 38 degrees on Sunday, including 38.8 degrees at Obihiro. According to Meteo-France's Etienne Kapikian, the previous May record was 37.2 degrees from 1993.