Parts of Japan are facing a divide of extreme weather today, with intense heat in the south and thunderstorms in the north [1].

This volatility highlights the dangerous combination of a persistent high-pressure ridge and shifting moisture patterns, increasing the risk of heatstroke and flash flooding across the archipelago.

Weather officials forecast that temperatures will rise above 40°C [1] in the Kyushu, Shikoku, and Tokai regions [1]. This extreme heat is attributed to a persistent high-pressure ridge and a broader hot summer pattern [2].

In the Tokai region, Nagoya is expected to reach a high of 39°C [1]. Other major cities are seeing significant heat, with Osaka forecasted at 38°C [1], Fukuoka at 37°C [1], and Tokyo at 36°C [1]. Western Japan is also expected to experience tropical nights with temperatures remaining near 30°C [1].

Meanwhile, moist air is moving into the northern and eastern regions of the country. A TBS NEWS DIG weather reporter said, "Today, due to the influence of humid air, there is a risk of rain or thunderstorms in some parts of Northern and Eastern Japan, mainly on the Pacific side" [1].

In the north, Sapporo is expected to be significantly cooler with a forecasted high of 28°C [1]. However, the threat of sudden thunderstorms remains for those on the Pacific coast of Hokkaido and Tohoku [1, 2].

Looking ahead, officials are monitoring Typhoon No. 13. The storm is expected to bring volatile weather to the southwestern islands after Thursday [1].

A TBS NEWS DIG weather reporter said, "Temperatures will rise mainly in Kyushu, Shikoku, and the Tokai region, and there will be places where it will be an extremely hot day of 40°C or more" [1].

“Temperatures will rise mainly in Kyushu, Shikoku, and the Tokai region, and there will be places where it will be an extremely hot day of 40°C or more”

The simultaneous occurrence of 40°C heat in the south and thunderstorms in the north demonstrates the high atmospheric instability currently affecting Japan. The looming threat of Typhoon No. 13 further compounds the risk, suggesting a period of prolonged climate stress for the nation's infrastructure and public health systems.