Click on a day for an hourly weather forecast
The weather in Koh Yao Yai in September is very hot. The average temperatures are between 24°C and 31°C, drinking water regularly is advisable.
There’s going to be many days of rain during the month of September in Koh Yao Yai.
Koh Yao Yai should expect an average of 15 to 22 days of rain, so be sure to bring along a waterproof jacket to stay dry this month!
Our weather forecast can give you a great sense of what weather to expect in Koh Yao Yai in September 2025.
If you’re planning to visit Koh Yao Yai in the near future, we highly recommend that you review the 14 day weather forecast for Koh Yao Yai before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 31° / 20° | 1 | 30 | 0 | 14 mm | Good | Koh Yao Yai in January |
| February | 35° / 23° | 1 | 28 | 0 | 12 mm | Ok | Koh Yao Yai in February |
| March | 37° / 25° | 2 | 29 | 0 | 50 mm | Ok | Koh Yao Yai in March |
| April | 37° / 27° | 6 | 24 | 0 | 122 mm | Ok | Koh Yao Yai in April |
| May | 35° / 26° | 9 | 22 | 0 | 187 mm | Bad | Koh Yao Yai in May |
| June | 33° / 25° | 11 | 19 | 0 | 201 mm | Ok | Koh Yao Yai in June |
| July | 32° / 24° | 14 | 17 | 0 | 267 mm | Ok | Koh Yao Yai in July |
| August | 31° / 24° | 15 | 16 | 0 | 292 mm | Ok | Koh Yao Yai in August |
| September | 31° / 24° | 16 | 14 | 0 | 351 mm | Ok | Koh Yao Yai in September |
| October | 30° / 23° | 10 | 21 | 0 | 258 mm | Ok | Koh Yao Yai in October |
| November | 30° / 21° | 2 | 28 | 0 | 53 mm | Good | Koh Yao Yai in November |
| December | 29° / 19° | 0 | 31 | 0 | 10 mm | Good | Koh Yao Yai in December |