When Does the Rainy Season Start in Kanto? Average Timing and Forecast Signals

If you live in the Kanto area, the rainy season usually becomes a concern from late May to early June.
According to JMA's confirmed historical data, the average start for Kanto-Koshin is around June 7.

That said, the date can move a lot depending on the year.
Some years start earlier, while others are much later.

What “Kanto” means in JMA announcements

JMA does not announce the rainy season start for Tokyo alone.
It announces it for the broader Kanto-Koshin region.

What to watch

Readers can watch three things:

Whether cloudy or rainy days continue in the weekly forecast
Whether the seasonal front is likely to stay near Japan
Whether the flow looks earlier or later than the normal early-June timing

Important note

JMA does not publish a simple long-range statement like “the rainy season will start on June X.”
It announces that the rainy season has “likely started” after considering recent weather and the outlook ahead.