Japan's All-Time Hottest Temperature of 41.2°C Recorded in Kaibara, Hyogo Prefecture on July 30, 2025

On the afternoon of July 30, 2025, Kaibara in Tanba City, Hyogo Prefecture, recorded an unprecedented 41.2°C, setting a new all-time high temperature for Japan. This surpasses the previous record of 41.1°C, which was jointly held by Kumagaya City in Saitama Prefecture (recorded on July 23, 2018) and Hamamatsu City in Shizuoka Prefecture (recorded on August 17, 2020).

On the same day, the Japanese archipelago was hit by intense heat across various regions, with temperatures exceeding 40°C in multiple locations. These included 40.6°C in Fukuchiyama City, Kyoto Prefecture, 40.3°C in Kuse, Maniwa City, Okayama Prefecture, and 40.0°C in Nishiwaki City, Hyogo Prefecture. For the Kinki region, this marked the first time in 31 years that temperatures topped 40°C, while for the Chugoku region, it was the first time ever in recorded history.

This record-breaking heatwave led to incidents such as the emergency transport of three men in their 80s in Tanba City, suspected of suffering from heatstroke. Strict warnings about heatstroke are being issued across the country. Local citizens expressed concerns about the impact on Tanba City's specialty products, such as chestnuts and black soybeans, with comments like 'It feels like everything is scorching' and 'I hope we can harvest them safely.' Tanba City is also known for the excavation of fossils of new dinosaur species, in addition to its chestnuts and black soybeans.

Furthermore, on the same day, tsunami warnings were issued along coastal areas across Japan due to a major earthquake off the Kamchatka Peninsula in Russia. This combination of extreme heat and tsunami threats led to a widespread perception on social media of it being a 'dangerous day.' The Japan Meteorological Agency and local governments continue to strongly urge residents to take precautions against heatstroke and to evacuate in areas at risk of tsunamis.

The context

Tanba City, located in Hyogo Prefecture, lies inland, far from the coast. Its basin-like topography often contributes to higher summer temperatures due to the 'heat island' effect and trapped heat. The city is renowned for its agricultural products, particularly 'Tanba chestnuts' and 'Tanba black soybeans,' which are highly prized. The region is also recognized internationally for paleontological discoveries, including the excavation of dinosaur fossils like Tambatitanis. Japan experiences hot and humid summers, and heatwaves are common, but temperatures exceeding 40°C are still relatively rare and pose a significant health risk, particularly for the elderly. The 41.2°C record in Kaibara underscores the increasing severity of heatwaves in the country, aligning with global trends of rising temperatures.