Seto Inland Sea 瀬戸内海
The Seto Inland Sea is an inland sea in Japan. It is one of the 115 sights listed on this site and is the 25th most looked-up sight in the country on English Wikipedia.
Planning a visit
The climate varies throughout the year. The warmest months are July, August, and September, with daily highs reaching 26 °C to 30 °C. The coolest period is from December to February, when daily highs are between 9 °C and 12 °C. June and July are the wettest months, with about 14 to 16 rainy days each.
To reach the area, you can fly into Hiroshima Airport, which is 48 km away. The sea is located about 604 km from Tokyo. The area covers approximately 19,700 km² and includes parts of Wakayama, Osaka, Hyōgo, and Okayama Prefectures.
Weather by month
The warmest month is August, with an average high of 30 °C. The wettest is June, with about 212 mm of rain.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Average high, °C | 9 | 10 | 12 | 17 | 21 | 24 | 28 | 30 | 26 | 21 | 16 | 12 |
| Average low, °C | 5 | 5 | 8 | 12 | 16 | 20 | 24 | 26 | 23 | 17 | 12 | 8 |
| Rainfall, mm | 53 | 72 | 112 | 122 | 156 | 212 | 185 | 108 | 174 | 111 | 77 | 48 |
| Rainy days | 6 | 7 | 10 | 11 | 10 | 14 | 16 | 13 | 15 | 10 | 8 | 7 |
Temperatures and rainfall: 1981–2010 averages for this spot (4 km grid), from CHELSA. Rainy days: 2015–2024, NASA POWER.
