Click on a day for an hourly weather forecast
The temperatures in Waterloo in September are comfortable with low of 12°C and and high up to 21°C.
You can expect about 3 to 8 days of rain in Waterloo 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 Waterloo in September 2025.
If you’re planning to visit Waterloo in the near future, we highly recommend that you review the 14 day weather forecast for Waterloo before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | -4° / -9° | 6 | 5 | 20 | 93 mm | Awful | Waterloo in January |
| February | -3° / -9° | 5 | 5 | 18 | 83 mm | Awful | Waterloo in February |
| March | 3° / -4° | 8 | 11 | 12 | 95 mm | Awful | Waterloo in March |
| April | 10° / 2° | 9 | 16 | 6 | 124 mm | Awful | Waterloo in April |
| May | 18° / 8° | 8 | 23 | 0 | 118 mm | Ok | Waterloo in May |
| June | 22° / 13° | 7 | 23 | 0 | 126 mm | Ok | Waterloo in June |
| July | 25° / 16° | 8 | 23 | 0 | 144 mm | Good | Waterloo in July |
| August | 25° / 15° | 6 | 25 | 0 | 118 mm | Perfect | Waterloo in August |
| September | 21° / 12° | 5 | 25 | 0 | 89 mm | Good | Waterloo in September |
| October | 14° / 6° | 7 | 22 | 1 | 120 mm | Ok | Waterloo in October |
| November | 6° / 0° | 7 | 14 | 9 | 81 mm | Awful | Waterloo in November |
| December | 0° / -4° | 6 | 7 | 17 | 85 mm | Awful | Waterloo in December |