Most of Japan has a rainy season, called tsuyu, in early summer, and it starts and ends on different dates depending on where you are. This sheet uses the average dates that Japan Guide’s rainy season page quotes from the Japan Meteorological Agency. The overlap rule at the end is our own. The dates are long-run averages, not a forecast.
The dates
| Region | Average start | Average end |
|---|---|---|
| Okinawa | 8 May | 23 June |
| Southern Kyushu | 29 May | 13 July |
| Shikoku | 4 June | 17 July |
| Kansai (Osaka, Kyoto) | 6 June | 19 July |
| Kanto (Tokyo) | 8 June | 20 July |
| Northern Tohoku | 12 June | 27 July |
Japan Guide says the season is caused by cold northerly and warm southerly air masses meeting over the islands, that it hits Okinawa about a month before the mainland, and that Hokkaido and the Ogasawara Islands are much less affected.
How to use it
- Find the region you will be in on each day of the trip.
- Compare your dates with the start and end. If any day falls between them, call it overlap and plan on carrying a folding umbrella daily.
- If you are within two weeks either side, call it edge. A compact umbrella in the bag costs you very little.
- Further away is clear for the rainy season. It does not mean dry: Wikipedia’s Climate of Japan entry says precipitation is above 25 mm in nearly every month of the year across most of the country.
A route from Okinawa to Tokyo in late May is a good example: the Okinawa leg overlaps, the Tokyo leg is an edge, and you would carry the umbrella throughout.
What the rainy season is like
Japan Guide says it does not rain every day. In Tokyo the chance of rain on a given day at the peak is 45 percent against 27 percent for sunny weather, and about half of the rainy days see only light rain. That favours a small folder over a big golf umbrella. Our chance of rain sheet explains what a rain percentage means.
Check the typhoons separately
Japan Guide says typhoon season peaks in August and September and that typhoons usually bring rain and wind to wide parts of the country for about two days. That is an indoor-plan question, not an umbrella question. Our wind speed chart and windproof umbrella checklist show what an umbrella can and cannot take.
Related sheets
City-break rain odds, South Africa rain days by month, how to choose a compact travel umbrella and wet umbrella on a train, bus or subway.
One example
XZVZX and Calm Eden share an owner. Calm Eden’s guide to whether you need an umbrella in Japan goes through typhoon months, summer sun and local umbrella habits. Its Haven Umbrella listing says it is made in Japan, with 30 carbon fibre ribs, an SPF 50+ canopy and a folded length of 40 cm (15.75 in).
Short version
- Rainy season dates run from about early May in Okinawa to late July in northern Tohoku.
- Overlap or edge: carry a folder. Clear: still keep one small, since rain happens in most months.
- Check typhoons on their own, especially in August and September.
Sources: Japan Guide (rainy season page, quoting the Japan Meteorological Agency) and Wikipedia, read on 29 October 2026. The overlap rule is our own.
Common questions
Where do these dates come from?
Japan Guide's rainy season page, which quotes average start and end dates from the Japan Meteorological Agency. They are long-run averages; a given year can start or end earlier or later.
What do overlap, edge and clear mean?
They are our own rule of thumb. Overlap means any day of your trip falls between the average start and end dates, edge means your trip is within two weeks either side, and clear means it is further away.
Does it rain all day in the rainy season?
No. Japan Guide says it does not rain every day: in Tokyo the chance of rain on a given peak day is 45 percent against 27 percent for sunny weather, and about half of the rainy days see only light rain.
What about typhoons?
Japan Guide says typhoon season peaks in August and September and that a typhoon usually brings rain and wind to wide parts of the country for about two days. That is a separate check from the rainy season.
Is this a forecast?
No. Check the Japan Meteorological Agency forecast in the week before you travel.