Japan - weather in September

September is the first autumn month in Japan, however, in the center-south it is still a hot, muggy and rainy month, while in the north it is a very mild or pleasantly warm month.

The daily average temperature is 17 °C (62.5 °F) in the north of the island of Hokkaido (see Abashiri) and 18.5 °C (65 °F) in Sapporo.
On the island of Honshu, the average is 20 °C (68 °F) in the far north (see Aomori), 21.5 °C (70.5 °F) in Sendai, in the northeast, and 23 °C (73.5 °F) in Niigata, in the northwest. In the south-east, the average is 24 °C (75 °F) in Tokyo, while further west, on the coast of the Seto Inland Sea (see Hiroshima, Okayama, Osaka, Kobe, Kyoto), it is 25/25.5 °C (77/78 °F), and reaches almost 27 °C (80.5 °F) in the south of the island of Kyushu (see Kagoshima).
On the small southern islands (see Okinawa, Ishigaki), which were much warmer the rest of the year, the average temperature is around 28 °C (82.5 °F).
Sometimes heat waves can still occur, during which the temperature can reach 37/38 °C (99/100 °F) in the main cities of central and southern Japan.

As for the rains, they are quite frequent and abundant everywhere. In fact, September is the second wettest month of the year after June, and is about the same as July. In some cities directly exposed to southerly winds, such as Kochi and Shizuoka, more than 300 mm (12 in) fall in the month.

An additional amount of rainfall, which raises the averages, is brought by typhoons, the tropical cyclones of the western Pacific. We are in the month in which the most intense typhoons occur in Japan, within the period, from August to the beginning of October, in which they are most likely. The areas most at risk are, in addition to the small southern islands, the south-facing coasts, directly on the ocean, of the islands of Kyushu, Shikoku and Honshu.

In Hokkaido, starting from mid-September in the mountains and at the end of the month at sea level, the period begins in which one can go tree hunting (momijigari), in particular maples, which become red. In the following months, this will happen in the rest of Japan.

In September, the sea in Japan is warm enough for swimming, as well as on the small southern islands, on the islands of Kyushu and Shikoku, and also on the island of Honshu, except in the northernmost part (see Aomori), where the sea is a little cool. Instead, on the island of Hokkaido, it is very cool on the west coast (see Sapporo), and even cold on the north coast (see Abashiri).

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Monthly climate averages - September

(from north to south)






















See also: Japan, the weather in August - October
The climate of Japan