Rainy Season 2025: Umbrella Weather in Japan

The Japan Meteorological Agency announced that Southern Kyūshū entered the rainy season on May 16, marking the first time tsuyu had descended on the region ahead of usual leaders Okinawa and Amami Ōshima since records began in 1951. Amami Ōshima subsequently entered the rainy season on May 19, followed by Okinawa on May 22. The rest of Japan’s main islands are expected to start tsuyu in June.

In 2024, the rainy season began around one or two weeks later than average in most regions around Japan, with areas from Northern Kyūshū to the east of the country entering tsuyu successively over the course of a week from June 17. However, in many areas tsuyu ended around the yearly average or a little earlier, making for a short rainy season.

In an average year, the rainy season begins in early June in areas from northern Kyūshū to Kantō Kōshin—which includes the cities of Tokyo, Osaka, Nagoya, and Fukuoka—and ends around July 20. Precipitation for this period is around 500 to 600 millimeters in northern Kyūshū and 300 millimeters in the Kantō Kōshin and Tōkai regions.

Precipitation Varies from Year to Year

The chart below shows the amount of rainy season precipitation in the Kantō Kōshin region (including Tokyo) over the past 30 years in comparison to the amount in an average year. The quantity varies considerably from year to year. For example, during the 1990 tsuyu, the Kantō region saw only half the normal amount of rainfall. In contrast, the 2020 rainy season stretched until August 1 and dumped 1.7 times the normal amount of precipitation.

(Translated from Japanese. Banner photo © Pixta.)