The Japan Meteorological Agency announced on June 7, 2026, that the Kanto-Koshin and Tokai regions have officially entered the rainy season [1].
The transition marks a critical period for Japan's agricultural cycle and urban infrastructure management, as the country prepares for a week of cloudy and rainy conditions.
The announcement was made at 11 a.m. [2]. According to the agency, the timing of the rainy season's arrival is roughly average for the year [3]. The weather shift is attributed to an active front bringing moist air and low-pressure systems moving along the southern coast of Japan [4].
In the Tokai region, the rainy season began one day later than the climatological average [5]. This onset is 21 days later than the start date recorded in the previous year [6].
The Kanto-Koshin region entered the rainy season on the same day as the climatological average [7]. However, this arrival is 16 days later than the start date seen last year [8].
Officials said the current atmospheric conditions will likely maintain these wet patterns throughout the coming week [4]. The agency continues to monitor the movement of low-pressure systems to provide updated forecasts for the affected regions [1].
“the Kanto-Koshin and Tokai regions have officially entered the rainy season”
The arrival of the rainy season, or 'tsuyu,' is a defining meteorological event in Japan that influences everything from crop yields to disaster preparedness. While the timing this year aligns with long-term averages, the significant delay compared to 2025 suggests a shift in regional weather patterns that may affect early-summer water management and agricultural planning.
