In September warmest sea in Japan is usually observed in the following locations: Okinawa, Nagasaki, Fukuoka.
Table below shows the average sea water temperature for marine resorts of Japan in September for the last three years.
| Place name | September 2026 | September 2025 | September 2024 |
|---|---|---|---|
| Okinawa | 83.3°F | 85.9°F | 85.3°F |
| Nagasaki | 83.2°F | 83.9°F | 83.8°F |
| Fukuoka | 82.3°F | 83.2°F | 82.6°F |
| Kobe | 82.1°F | 81.5°F | 82.7°F |
| Osaka | 82.1°F | 82.5°F | 83.4°F |
| Nara | 81.8°F | 82.6°F | 83.6°F |
| Nagoya | 80.6°F | 82.2°F | 84.0°F |
| Hiroshima | 80.5°F | 81.4°F | 82.2°F |
| Kyoto | 80.4°F | 82.6°F | 84.0°F |
| Tokyo | 80.0°F | 81.6°F | 81.9°F |
| Yokohama | 79.5°F | 80.9°F | 81.6°F |
| Kamakura | 79.2°F | 79.6°F | 81.0°F |
| Atami | 79.1°F | 79.7°F | 81.1°F |
| Hakone | 79.0°F | 79.4°F | 81.1°F |
| Sapporo | 72.1°F | 73.2°F | 72.2°F |
| Noboribetsu | 69.3°F | 71.1°F | 71.5°F |
Charts below show average sea water temperature for Japan resorts with the warmest sea in September.
You can also check other months of the year to see sea temperature of Japan resorts at that time.
Places in Japan:
Name
°F
