Click on a day for an hourly weather forecast
The weather in Jeju in September is hot. The average temperatures are between 21°C and 25°C.
You can expect rain for roughly half of the month of September in Jeju. We’re expecting roughly 8 to 15 days of rain, so your rubber boots and umbrella are going to see plenty of use this month if you’re keen on staying dry.
Our weather forecast can give you a great sense of what weather to expect in Jeju in September 2026.
If you’re planning to visit Jeju in the near future, we highly recommend that you review the 14 day weather forecast for Jeju before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 7° / 4° | 7 | 18 | 6 | 95 mm | Awful | Jeju in January |
| February | 8° / 5° | 7 | 18 | 3 | 104 mm | Awful | Jeju in February |
| March | 11° / 7° | 7 | 23 | 1 | 123 mm | Bad | Jeju in March |
| April | 15° / 11° | 6 | 24 | 0 | 147 mm | Good | Jeju in April |
| May | 19° / 15° | 5 | 26 | 0 | 143 mm | Good | Jeju in May |
| June | 23° / 19° | 7 | 23 | 0 | 218 mm | Good | Jeju in June |
| July | 27° / 23° | 9 | 22 | 0 | 301 mm | Good | Jeju in July |
| August | 28° / 24° | 8 | 23 | 0 | 277 mm | Good | Jeju in August |
| September | 25° / 21° | 8 | 22 | 0 | 286 mm | Good | Jeju in September |
| October | 20° / 17° | 3 | 28 | 0 | 152 mm | Good | Jeju in October |
| November | 15° / 11° | 5 | 25 | 0 | 103 mm | Good | Jeju in November |
| December | 9° / 6° | 8 | 21 | 3 | 92 mm | Awful | Jeju in December |