Weathernews reported Tokyo and Osaka reached 30°C on Wednesday, Oct. 21, the latest date on record for both cities to meet Japan’s “midsummer day” threshold.
The Japan Meteorological Agency (JMA) uses that term for a day with a high of at least 30°C. JMA data show Osaka reached 31.2°C. Weathernews reported Tokyo’s crossing of the threshold.
JMA historical records show Tokyo’s previous latest 30°C day was Oct. 19, 2024, while Osaka’s was Oct. 20, 1933. Weather observations in Tokyo began in 1875. Official observations at the Osaka station began in 1883.
Weathernews linked the warmth to southerly air moving toward a low-pressure area and front. AFP reported unusually high temperatures along parts of Japan’s Pacific coast as warm, humid air moved north.
Japan’s average temperature in summer 2025 was 2.36°C above the 1991–2020 baseline, the JMA said. It was the warmest summer in the agency’s national series, which began in 1898.
