The rainy season has not yet set in only West Japan.

Hello.
This is May in Japan.

The rainy season doesn't start yet in West Japan.

In South Kyushu and Okinawa, the rainy season set in by the end of May.
In East Japan, the rainy season set in by the middle of June.
The rainy season has not yet set in only West Japan.

In North Kyusyu, the water supply is going to fail.
We have to pray for rain !!