Click on a day for an hourly weather forecast
The temperatures in Watertown in September are comfortable with low of 15°C and and high up to 23°C.
You can expect about 3 to 8 days of rain in Watertown 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 Watertown in September 2025.
If you’re planning to visit Watertown in the near future, we highly recommend that you review the 14 day weather forecast for Watertown before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 1° / -5° | 5 | 18 | 8 | 51 mm | Awful | Watertown in January |
| February | 2° / -5° | 4 | 15 | 9 | 56 mm | Awful | Watertown in February |
| March | 7° / -1° | 6 | 19 | 6 | 61 mm | Bad | Watertown in March |
| April | 13° / 5° | 6 | 24 | 1 | 55 mm | Ok | Watertown in April |
| May | 19° / 10° | 4 | 27 | 0 | 47 mm | Good | Watertown in May |
| June | 24° / 14° | 5 | 25 | 0 | 56 mm | Perfect | Watertown in June |
| July | 28° / 18° | 5 | 26 | 0 | 62 mm | Perfect | Watertown in July |
| August | 28° / 18° | 4 | 27 | 0 | 58 mm | Perfect | Watertown in August |
| September | 23° / 15° | 3 | 27 | 0 | 39 mm | Perfect | Watertown in September |
| October | 17° / 9° | 5 | 26 | 0 | 59 mm | Good | Watertown in October |
| November | 10° / 3° | 4 | 25 | 1 | 44 mm | Ok | Watertown in November |
| December | 5° / -1° | 5 | 20 | 6 | 55 mm | Awful | Watertown in December |