Photo/Illutration A pedestrian with a parasol in Tokyo’s Ginza district on July 7. Many people were out and about in the capital despite heatstroke warnings. (Koichi Ueda)

Relentless summer heat combined with the start of a three-day weekend that is bound to see a sharp uptick in domestic travel prompted authorities Sept. 14 to warn people to be on alert for heatstroke.

The Japan Meteorological Agency and the Environment Ministry issued heatstroke alerts for a total of 18 locations, including Tokyo, Saitama, Chiba, Kanagawa and Yamanashi prefectures in the Kanto-Koshin region, Kyoto, Hyogo and Wakayama prefectures in the Kinki region, and Fukui Prefecture in the Hokuriku region.

According to the JMA, the mercury in Tokyos Chiyoda Ward hit 32.9 degrees at 10 a.m. The corresponding figure for Koshigaya in neighboring Saitama Prefecture was 33 degrees and 33.8 degrees in Mobara, Chiba Prefecture.

Of the 914 observation points nationwide, 366 recorded temperatures of 30 degrees or higher.

As the 13th typhoon of the season approaches the Amami and Okinawa regions, officials warned that the weather in western Japan is expected to be unstable in some places on Sep. 15 and 16.

High temperatures are expected to continue nationwide.