Click on a day for an hourly weather forecast
The temperatures in St. Thomas in September are usually low and can range between 11°C and 18°C.
You can expect about 3 to 8 days of rain in St. Thomas during the month of September. It’s a good idea to bring along your umbrella so that you don’t get caught in poor weather.
Our weather forecast can give you a great sense of what weather to expect in St. Thomas in September 2025.
If you’re planning to visit St. Thomas in the near future, we highly recommend that you review the 14 day weather forecast for St. Thomas before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 8° / 4° | 9 | 20 | 2 | 100 mm | Awful | St. Thomas in January |
| February | 8° / 4° | 8 | 18 | 3 | 91 mm | Awful | St. Thomas in February |
| March | 10° / 4° | 6 | 24 | 1 | 70 mm | Ok | St. Thomas in March |
| April | 12° / 5° | 5 | 25 | 0 | 64 mm | Ok | St. Thomas in April |
| May | 15° / 8° | 5 | 26 | 0 | 70 mm | Good | St. Thomas in May |
| June | 18° / 11° | 5 | 25 | 0 | 79 mm | Good | St. Thomas in June |
| July | 20° / 13° | 5 | 26 | 0 | 73 mm | Good | St. Thomas in July |
| August | 19° / 13° | 5 | 26 | 0 | 78 mm | Good | St. Thomas in August |
| September | 18° / 11° | 4 | 26 | 0 | 61 mm | Good | St. Thomas in September |
| October | 15° / 10° | 7 | 24 | 0 | 117 mm | Ok | St. Thomas in October |
| November | 11° / 7° | 8 | 22 | 0 | 122 mm | Bad | St. Thomas in November |
| December | 9° / 5° | 9 | 21 | 1 | 108 mm | Bad | St. Thomas in December |