Many parts of Japan were blanketed by sweltering heat on Sunday. Weather officials forecast that the heatwave will continue for the next seven days.

Daytime temperatures reached 38.6 degrees Celsius in Isesaki, Gunma Prefecture, 38.4 in Kumagaya, Saitama Prefecture, 37.4 in Kyoto City and 35 in central Tokyo.

Temperatures rose above 35 degrees at 168 observation points across Japan, or nearly 20 percent of the total.

A daytime high of 38 degrees is expected on Monday in Kyoto City, Yonago in Tottori Prefecture and Fukui City.

The mercury will top 35 in many parts of the country.

People are advised to refrain from going outside and to avoid exercising during the daytime if possible.

They are also being urged to use air conditioners and remove masks when they are outdoors and are not talking much.

The Meteorological Agency says temperatures will remain dangerously high until August 7 in eastern and western Japan and Okinawa.

Tropical storm Trases developed near the Okinawa main island on Sunday, intermittently bringing rain and strong winds to the island and the Amami region in Kagoshima Prefecture.

The damp air from the storm and from a high-pressure system in the Pacific is causing unstable atmospheric conditions from southern Tohoku to western Japan.

Radar analysis indicates that about 100 millimeters of rain fell in an hour near Kawakami Village, Nagano Prefecture, on Sunday afternoon.

A mudslide alert has been issued for parts of Nagano, Fukushima and Miyazaki prefectures.

Torrential rain of more than 50 millimeters per hour could fall on Sunday evening in Okinawa, southern Kyushu and the Kanto-Koshin region.

The agency is urging people to watch out for mudslides, floods in low-lying areas and rising rivers as well as lightning strikes and gusts, including tornadoes.

Caution against strong winds and high waves is also advised in Okinawa, Amami and Kyushu.