If you thought last summer was hot, well… the 2025 season was officially Japan's hottest on record, and the scorching temperatures across the country are now expected to last through September.
According to the Japan Times, the Japan Meteorological Agency reported that this summer, nationwide temperatures averaged some 2.36 degrees Celsius above normal.
On August 5, the city of Isesaki in Gunma prefecture broke the country’s all-time heat record, with the mercury reaching a whopping 41.8 degrees. Additionally, the cumulative number of ‘extremely hot days’ (days when the high is at least 35 degrees) reached a total of 9,385, which surpasses the 2024 record of 8,821 days.
According to the JMA, the extreme heat is being driven by global warming and a strong Pacific high-pressure system influenced by weather patterns near the Indian Ocean and the Philippines. And, unfortunately, it doesn't look like it will be cooling down anytime soon. This heatwave is expected to last well into September, with the JMA forecasting an 80 percent chance of above-average temperatures nationwide.
Additionally, autumn will likely arrive later than usual, as high sea surface temps near the Philippines and westerly winds pushing farther north mean warmer-than-normal weather in October and November too.
In the meantime, to help you stay safe and assess the risk of heatstroke, be sure to check out this handy Tokyo heat map and stock up on items to help you keep cool.
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