With Japan now in its rainy season, the greater Tokyo area will be seeing partly cloudy skies and showers for much of the week. Daytime temperatures will be humid and mainly in the upper 20s°C (80s°F). Evening lows will be warm, in the low 20s°C.

What clothes to pack for Tokyo in June?
・Light clothes for summer; short-sleeved shirts; jeans or light slacks; comfortable sneakers or walking shoes are recommended.
・Folding umbrella

Japan nationwide
Looking at the weather forecast for the rest of Japan, most areas will be seeing overcast skies, showers, and hot temperatures.

Northern Japan
Hokkaido and the north country are expected to see mostly cloudy skies this week with rain in the beginning of the week and Sunday. Daytime highs will be in the mid-upper 20s. Evening temperatures will be in the upper teens.

Central Japan
The greater Osaka and Kyoto area is expected to see cloudy skies and showers throughout the week. Temperatures will be hot, with highs in the upper 20s °C and lows in the low to mid-20s °C.

Okinawa
As for Okinawa, expect partly cloudy skies for much of the week in Naha. Daily highs are expected to be in the lower 30s℃, with lows in the upper 20s.

No tropical storms are currently in the forecast for Japan.

Details on storms can be found on the Japan Meteorological Agency website.

Check the links below for more on upcoming fun events and festivals!

・Latest Typhoons/Tropical Cyclone Information: http://www.jma.go.jp/en/typh/
・Latest Earthquake Information: http://www.jma.go.jp/en/quake/

Source for forecast and images: Japan Meteorological Agency website / http://www.jma.go.jp/jma/indexe.html