Japan Endures Record-Breaking Heatwave, Signaling Accelerated Warming Trend
TOKYO – Japan experienced its hottest summer on record, with national average temperatures exceeding previous highs and shattering local records across the country, the Japan Meteorological Agency (JMA) announced September 1st. The period from June to August saw temperatures 2.36 degrees celsius above average, marking a significant jump from recent years and raising concerns about an accelerating rate of warming.
This summer’s heat builds upon a trend of increasingly severe summers, representing the third consecutive year Japan has broken its national heat record. Though, the margin by which this summer surpassed previous records – a 0.6 degree Celsius increase over the 1.76 degree celsius anomaly seen in both 2023 and 2024 – suggests a potentially faster pace of temperature rise. The escalating heat poses risks to public health, agriculture, and infrastructure, demanding increased preparedness and mitigation efforts.
The JMA attributes the extreme temperatures to a combination of atmospheric and oceanic factors.A northward shift in westerly winds brought warm air from the south over the Japanese archipelago. Together, both the Tibetan high, a high-pressure system originating in central asia, and the Pacific High, a high-pressure system over the Pacific Ocean, intensified, resulting in prolonged clear skies and increased solar radiation.
Across the nation, the heat manifested in numerous record-breaking temperatures. A total of 25 locations nationwide recorded temperatures of 40 degrees Celsius or higher. Of the 914 observation sites monitored by the JMA, 207 registered their highest-ever recorded temperatures.
the national high temperature record was broken twice this summer. On July 30th, Tamba, Hyogo Prefecture, reached 41.2 degrees Celsius, surpassing the previous record of 41.1 degrees Celsius set in both Hamamatsu,Shizuoka Prefecture (2020),and Kumagaya,Saitama Prefecture (2018). Though, this record was short-lived, with Isesaki city, Gunma Prefecture, reaching a new peak of 41.8 degrees Celsius on August 5th.
Several cities endured multiple days of extreme heat. Maebashi and Isesaki in Gunma Prefecture, Kumagaya and Hatoyama in Saitama Prefecture, and Kuwana in Mie Prefecture each experienced two days with temperatures exceeding 40 degrees Celsius. Hita, Oita Prefecture, suffered through 55 days where temperatures remained above 35 degrees Celsius, while Kyotanabe in Kyoto Prefecture and Kofu in Yamanashi Prefecture each recorded 53 such days.
Even Hokkaido, Japan’s northernmost main island, experienced unusually high temperatures due to a combination of the prevailing winds and elevated sea surface temperatures. Kitami recorded 39.0 degrees celsius on July 24th, while Obihiro reached 38.8 degrees Celsius and Saroma hit 38.6 degrees Celsius on the same day.
