Monday is shaping up to be another searing day especially in western Japan, and the Meteorological Agency is advising the public to take lots of water and stay in an air-conditioned room to gird against heatstroke.

The agency estimates the highest temperature during the day will reach 37 degrees Celcius in the cities of Osaka and Kyoto, 36 in Nagoya, Takamatsu, Kagawa Prefecture, Okayama and Kumamoto, 35 in Hiroshima, Kochi and Oita, and 34 in Fukuoka, NHK reported.

The public broadcaster said at least 510 people nationwide were transported to hospitals due to symptoms apparently of heatstroke by 5 p.m. Sunday. Two of them have died, and one was unconscious and in serious condition.

The day's mercury rose to 37.4 degrees in Bungo-Ono, Oita Prefecture, and 37 in Aki-Ota, Hiroshima Prefecture.

Sudden changes in weather are expected in wide areas of the nation in Monday afternoon. The weather agency is advising caution against violent thunderstorms and strong winds, NHK said.