Japan expects a widespread sunny spell on Tuesday, May 19, with temperatures reaching around 30°C [2] across much of the country.
This sudden surge in heat creates immediate public health risks, prompting officials to issue warnings against heat-stroke as temperatures climb well above seasonal norms.
A high-pressure ridge is bringing strong sunshine and heat to the region [1]. In Fukushima, temperatures are forecast to reach 35°C [1], which would qualify as an extremely hot day. This follows a trend from Monday, when the country recorded its first extremely hot day of the year [2]. Observations from Monday showed peak temperatures of 35.3°C in both Hita, Oita, and Toyooka, Hyogo [1].
Other major cities are also expected to see significant warmth on Tuesday. Forecasts include 31°C in Nagano, 29°C in Tokyo, Sendai, Niigata, and Aomori, and 28°C in Kanazawa [1]. Nagoya is also expected to reach 29°C [1]. Cooler temperatures remain in the north, with Sapporo forecast at 18°C and Kushiro at 16°C [1].
While the majority of the country remains sunny, weather conditions will shift in the south. Humid air flowing around the edge of the high-pressure ridge is expected to bring rain to Kyushu and Shikoku later in the day [1].
Residents are advised to take precautions against the heat, particularly in areas where the 30°C threshold is exceeded. The transition from extreme heat to rain in the southern islands marks a volatile shift in the regional weather pattern as the season progresses [1].
“Temperatures are expected to reach 30°C across much of the country”
The occurrence of 'extremely hot days' (moshobi) in May suggests an early arrival of summer-like conditions in Japan. The contrast between the high-pressure ridge causing heat in the center and the humid air bringing rain to the south illustrates the complex atmospheric instability typical of the region's transition into the rainy season.
