Three people died and some 490 were taken to hospital due to heatstroke or heat exhaustion Thursday, a Kyodo News tally showed, as temperatures soared across much of Japan.

Of 929 Meteorological Agency observation points nationwide, more than 400 logged highs of at least 30 degrees Celcius, while the mercury topped 35 C at 51 locations.

The mercury reached the season's highest, 38.8 C, in the city of Koshu in Yamanashi Prefecture, and 38.6 C in Kawanehoncho, Shizuoka Prefecture. In Tokyo's Nerima Ward, the temperature rose to 37.7 C.

The weather agency said a high-pressure system covering the Japanese archipelago sent a blanket of hot air over a wide swath of the country.

Temperatures in eastern Japan were expected to remain high on Friday, while in western and southwestern Japan a low-pressure system was expected to bring heavy rain from Friday through Saturday.

In the city of Shikokuchuo, Ehime Prefecture, an 88-year-old woman who had been working on a farm collapsed and was taken to a hospital where she was pronounced dead. An 81-year-old woman in the town of Misato, Saitama Prefecture, who had been working on a farm also died of similar causes.

In Hashimoto, Wakayama Prefecture, a 36-year-old man who was working outside a factory was also taken to a hospital after being found collapsed. He also died.