The Japan resorts with the warmest sea water temperature in April are Okinawa, Nagasaki and Atami.
Below you can see a list of all popular Japan resorts and information about sea water temperature in April for the last two years.
| Resort Name | April 2026 | April 2025 | April 2024 |
|---|---|---|---|
| Okinawa | 77.1°F | 73.9°F | 76.0°F |
| Nagasaki | 65.5°F | 62.7°F | 64.4°F |
| Atami | 63.2°F | 62.1°F | 63.8°F |
| Tokyo | 63.1°F | 60.1°F | 61.4°F |
| Hakone | 63.0°F | 62.3°F | 63.5°F |
| Kamakura | 62.7°F | 62.3°F | 63.4°F |
| Yokohama | 62.4°F | 60.7°F | 61.7°F |
| Fukuoka | 61.2°F | 59.6°F | 61.1°F |
| Nagoya | 61.0°F | 59.4°F | 61.1°F |
| Kyoto | 60.1°F | 58.2°F | 58.6°F |
| Osaka | 60.1°F | 58.4°F | 59.6°F |
| Nara | 60.0°F | 58.2°F | 59.3°F |
| Kobe | 59.6°F | 57.2°F | 58.6°F |
| Hiroshima | 59.4°F | 58.0°F | 59.4°F |
| Sapporo | 45.5°F | 44.3°F | 44.2°F |
| Noboribetsu | 39.5°F | 41.3°F | 40.7°F |
Please see following sea water temperature averages charts for the warmest Japan resorts in April.
You can also get the same information for the every other month of the year when the average sea water temperature is greater then 70°F.
