Japan's weather agencies forecast an increase in locations experiencing extremely hot days on Tuesday, Aug. 18 [1].
The spike in temperatures poses health risks for residents and disrupts daily planning, while providing a brief window for outdoor chores before potential rain.
A high-pressure system shifting slightly west is bringing warm air advection over western Japan [1]. This system, combined with moist air from the south, is pushing more cities past the "extremely hot day" threshold [1].
In Yonago, temperatures are expected to reach 36°C [1]. Other cities, including Kumamoto, Oita, Matsue, and Fukui, are forecast to hit 35°C [1].
Forecasts for other regions show varied heat levels. Niigata and Nagano are both expected to reach 34°C [1]. In the north, Sendai and Morioka are forecast at 29°C [1], while Aomori is expected to be 28°C [1]. Cooler temperatures are anticipated in Sapporo and Kushiro, both forecast at 26°C [1].
There is a discrepancy regarding the forecast for Nagoya. TBS NEWS DIG reported a high of 33°C [1], while tenki.jp forecast a higher 40°C [12].
Despite the heat, the weather may be favorable for some household tasks. "Tomorrow will be a chance to hang accumulated laundry outside," TBS NEWS DIG said [1].
However, the agencies warned that the clear skies may not last. Residents in mountainous and inland areas from western to eastern Japan should be alert for sudden showers starting in the afternoon [1].
"Please be careful of changes in the sky," TBS NEWS DIG said [1].
“Yonago is expected to reach 36°C.”
The interaction between the Pacific high-pressure system and southern moist air creates a volatile weather pattern. While the immediate effect is extreme heat in western Japan, the instability in inland and mountainous regions suggests a transition toward more erratic weather as the week progresses.
