Intense heat gripped eastern and western Japan on Thursday, with the temperature soaring above 39 degrees Celsius in Shizuoka City, central Japan.
Weather officials are urging people to take thorough precautions to prevent heatstroke.
The Meteorological Agency says a strong high-pressure system over eastern and western Japan has been pushing up temperatures on the Pacific side.
The agency says that by 2 p.m., the temperature hit a record high for Shizuoka City at 39.3 degrees.
The temperature also reached 35 degrees in central Tokyo for the first time this year.
In other places, the temperature rose to 37.6 degrees in Wakayama Prefecture's Shingu City, 36.9 degrees in Yamanashi Prefecture's Kofu City and 36.6 degrees in Gunma Prefecture's Kiryu City.
The mercury hit 36.5 degrees in Miyazaki City and Kochi Prefecture's Shimanto City, 36.0 degrees in Tokyo's Hachioji City and 35.1 degrees in Aichi Prefecture's Nagoya City.
Agency officials say that when temperatures suddenly rise around this time of year, an increasing number of people, particularly the elderly, are hospitalized due to possible heatstroke and some die.
The officials are calling on people to stay on alert for heatstroke. They're also urging the public to check an index provided by the Environment Ministry that indicates the heat stress a person feels in direct sunlight.
They say people should avoid exercising outdoors. They're also calling on people to use air conditioning and stay hydrated.