Temperatures across Japan soared Monday, with many areas in the Kanto region topping 30 degrees Celsius — levels on par with those of midsummer days.

As of noon, the mercury had hit 31.7 degrees Celsius in Kofu, Yamanashi Prefecture; 31.1 C in Kiryu, Gunma Prefecture; 30.5 C in Kumagaya, Saitama Prefecture; 30.7 C in Sano, Tochigi Prefecture, and 28.1 C in Tokyo, according to the Meteorological Agency.

The sudden jump in temperatures prompted warnings from the agency for the public to take measures needed to prevent heatstroke.

Information in English from the agency can be found on its website, at https://www.data.jma.go.jp/fcd/yoho/data/kouon/heat_illness.html .