Swimming in Japan in september 2025 Sea temperature by city in september

In september in Japan swimming conditions vary by city. Details below:

In september in Kochi, Okinawa, Osaka, Izumo, Kagoshima (Kyushu), Kobe, Nagasaki, Nago, Naha, Takamatsu, Tokushima, Aguni-jima, Goto islands, Higashi, Iheya-jima, Ise, Ishigaki-jima, Itoman, Izenajima, Kitakyushu, Kumano Kodo, Miyagi Island, Muroto, Tanega-shima, Tosashimizu, Yakushima, Yonaguni-jima, Yoron-jima, Beppu/Ōita, Karatsu, Matsuyama, Minamata, Miyazaki, Nichinan, Niihama, Nobeoka, Saiki, Sasebo, Shibushi Bay, Shingu, Tamano, Tateyama, Uwajima and Wakayama, swimming conditions are perfect! With water reaching a maximum of 83°F and an average of 81°F, going in the water (and staying there!) feels great.

As for Tokyo, Fukuoka, Hiroshima, Nagoya, Akita, Aomori, Hakone, Kanazawa, Okayama, Sendai (Honshu), Izu, Kamakura, Kure, Miyajima, Niigata, Sado island, Tottori, Wajima, Yokohama, Asahi, Chiba, Fuji, Hachinohe, Hamada, Hamamatsu, Hikari, Hitachi-Naka, Ishinomaki, Iwaki, Joetsu, Kamaishi, Kimitsu, Kurayoshi, Maizuru, Masuda, Miyako, Mutsu, Nagaoka, Nanao, Noshiro, Sakata, Shizuoka, Toyama and Ube, swimming is pleasant in september. The sea water is 78°F on average (min: 74°F/max: 82°F) so you can easily spend time in the water.

Swimming in september in Sapporo (Hokkaido), Hakodate, Monbetsu, Shiretoko National Park, Kushiro, Muroran, Otaru, Tomakomai and Wakkanai is possible but the sea is generally cool. So though the sea temperature may sometimes reach 74°F, it can also go as low as 65°F. Note that the average is 69°F.

Swimming in september in Abashiri and Nemuro is possible... with a wetsuit! Indeed, the water is cold at this time of year with an average temperature of 63°F (min: 58°F/max: 68°F).