Sweltering heat hit Japan on Sunday. The temperature shot up to over 37 degrees Celsius in the northernmost prefecture of Hokkaido.
The Meteorological Agency says the temperatures were already high in the morning due to hot air and strong sunshine.
In the city of Obihiro, Hokkaido, the mercury reached 37.5 degrees Celsius, a national record high for May.
Temperatures are expected to rise even further later in the day.
Daytime highs are expected to reach 35 degree across the country. The mercury is expected to hit 33 degrees in central Tokyo.
Authorities are advising people to take measures to prevent heatstroke.