Japan - weather in June

June is the first summer month in Japan, and it is a very mild month in the far north, where it still has spring characteristics, and progressively more warm and more muggy in the center-south. Rainfall also increases going south, and in some areas it is very abundant.

The daily average temperature is 14 °C (57 °F) in the north of the island of Hokkaido (see Abashiri) and 17.5 °C (63.5 °F) in Sapporo.
On the island of Honshu, the average is 18 °C (64.5 °F) in the far north (see Aomori), 19.5 °C (67 °F) in Sendai, in the north-east, and 21.5 °C (70.5 °F) in Niigata, in the north-west. In the south-east, the average is 22.5 °C (72.5 °F) in Tokyo, while on the southern coast of Honshu (see Osaka), but also on the islands of Kyushu (see Fukuoka, Kagoshima) and Shikoku, the average is 23.5/24 °C (74.5/75 °F).
On the small southern islands the temperature is higher, as the average is 27.5 °C (81.5 °F) in Okinawa and 28.5 °C (83.5 °F) in Ishigaki.

As for the rains, they are quite frequent in the north, while they are frequent and abundant in the south. In fact, on average, June is the rainiest month of the year in Japan.
In particular, in the center-south, in June and July is the period called Baiu or "plum rain", with abundant rainfall: in the south of the island of Kyushu (see Kagoshima), in this period, which here generally runs from May 29th to July 13th, even more than 500 mm (20 in) fall in a month. This very rainy period normally runs from June 6 to July 19 in Kyoto, June 8 to July 20 in Tokyo, and June 12 to July 27 in northern Honshu, where, however, the effects are less evident.
On the small southern islands (see Okinawa, Ishigaki), this very rainy period occurs a month earlier than on the main islands of Japan, ie in May and June.

June is generally the first month in which typhoons, the tropical cyclones of the western Pacific, can occur, although they will be more likely in the following months. Typhoons are more frequent on the small southern islands, but sometimes they can move northwards, affecting the main islands, starting from the southern coasts.

In June, the sea in Japan is warm enough for swimming, as well as on the small southern islands, on the south coast of the islands of Kyushu and Shikoku, and on the south coast of Honshu approximately up to Shizuoka, southwest of Tokyo.

Japan is located at medium latitudes, however, in June the days are quite long, especially in the north, where the sun remains above the horizon for more than 15 hours a day.
In the Northern Hemisphere, June is the month when the days are longest, and June 21st is the summer solstice.




See also: Japan, the weather in May - July
The climate of Japan