The Japan Meteorological Agency forecast intermittent heavy rain for Hokkaido and a heat wave reaching 36°C in Tottori and other western regions [1].
These divergent weather patterns present simultaneous risks of flooding in the north and heat-related illnesses in the south, complicating national emergency preparedness.
Weather forecasters said that Hokkaido will experience heavy rain starting the night of July 18 and continuing through July 20 [2]. This activity will affect both the Japan Sea and Pacific coasts of the region. The agency expects rainfall intensity to reach approximately 30 mm per hour [1]. In Sapporo, the forecasted maximum temperature is 26°C [1].
Meanwhile, western Japan is facing a significant heat wave. Tottori is expected to reach a maximum temperature of 36°C [1]. This spike in temperature, combined with high humidity nationwide, has led officials to issue heat-stroke alerts for western Japan [1].
The current weather is driven by a seasonal summer pattern. A low-pressure front is generating the heavy precipitation in Hokkaido, while a separate heat system pushes temperatures upward across the western provinces [1].
Residents in the affected areas are advised to monitor local updates as the low-pressure system moves. The combination of extreme heat and sudden heavy rain underscores the volatility of the current summer season, a trend that requires constant vigilance from local municipalities.
“Hokkaido will experience heavy rain starting the night of July 18 and continuing through July 20.”
The simultaneous occurrence of intense rainfall in the north and extreme heat in the west demonstrates the volatile nature of Japan's summer weather systems. When high humidity accompanies temperatures of 36°C, the risk of heatstroke increases significantly, while 30 mm per hour of rain can lead to rapid urban flooding and landslides, requiring a dual-pronged emergency response from national authorities.
