The temperature topped 30 Tuesday in Tokyo, marking a record 68 days on which the mercury has reached this threshold this year, the Meteorological Agency said.
The previous record of 67 days was set in 2000, it said.
The agency measured a temperature of 30.1 at 9:21 a.m. at the Otemachi observation post in central Tokyo, where measurements began in 1923.
The record represents yet another hot-weather landmark in the capital this year.
Aug. 12 marked a record 38th straight day above 30, breaking the record set in 1995, and on July 21, the temperature at Otemachi shot up to 39.5, the highest on record.
The agency said many places across Japan experienced hot days this summer due to a stronger-than-usual high pressure ridge in the Pacific and other causes, including the “heat island” effect in cities.
The heat island effect refers to high urban temperatures caused by buildings and pavement, emissions from vehicles, and heat from air conditioners.