Temperatures have shot up widely across eastern and northern Japan on Monday, with sunny weather prevailing.
Niigata Prefecture became the second place in the country to have temperatures exceeding 30 degrees Celsius this year, following the southern prefecture of Okinawa.
Weather officials say a high pressure system has been covering wide areas in eastern and northern Japan. They say the clear sky, along with warm air flowing into the Sea of Japan side from the south, has pushed up temperatures.
The day's maximum temperature, as of 2 p.m., climbed to 32.2 degrees in Sanjo City and 30.9 degrees in Nagaoka City, both in Niigata Prefecture.
Many other cities recorded maximum temperatures above 25 degrees, including 26.8 degrees in central Tokyo and 26.1 degrees in the northern city of Sapporo.
Weather officials are advising the public to be on alert for heatstroke as people may not yet have adapted to high temperatures.