In a foretaste of the hot summer ahead, a robust high-pressure system extended across a wide area from western to eastern Japan on May 20, bringing clear skies and elevated temperatures to many regions.
A total of 187 locations nationwide recorded temperatures of 30 degrees or higher, marking the highest number this year.
In Otsuki city in Yamanashi Prefecture, the mercury hit a scorching 34.0 degrees shortly after 2 p.m.
The Japan Meteorological Agency reported that a warm air influx from the south, around the periphery of a Pacific high-pressure system encompassing the Honshu region, combined with westerly winds bringing additional heat from the west, contributed to the significant rise in temperatures, particularly in inland areas.
In Hachioji, a city in western Tokyo, temperatures reached 33.5 degrees, while Itoshima in Fukuoka Prefecture and Asago in Hyogo Prefecture recorded highs of 33.0 degrees.
Central Tokyo reported its first instance of temperatures exceeding 30 degrees this year, hitting 31.1 degrees.
Looking ahead, temperatures are expected to remain above normal for this time of year with hot and humid conditions prevailing from May 21, despite the anticipated arrival of a weather front and moist air bringing rainfall mainly to western Japan.