Click on a day for an hourly weather forecast
The temperatures in Monticello in September are comfortable with low of 11°C and and high up to 22°C.
You can expect about 3 to 8 days of rain in Monticello 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 Monticello in September 2025.
If you’re planning to visit Monticello in the near future, we highly recommend that you review the 14 day weather forecast for Monticello before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | -8° / -14° | 3 | 11 | 18 | 27 mm | Awful | Monticello in January |
| February | -6° / -13° | 2 | 11 | 15 | 35 mm | Awful | Monticello in February |
| March | 3° / -4° | 6 | 14 | 11 | 73 mm | Awful | Monticello in March |
| April | 11° / 2° | 7 | 17 | 6 | 105 mm | Awful | Monticello in April |
| May | 19° / 9° | 8 | 23 | 1 | 132 mm | Ok | Monticello in May |
| June | 24° / 14° | 8 | 22 | 0 | 186 mm | Good | Monticello in June |
| July | 27° / 17° | 7 | 24 | 0 | 144 mm | Good | Monticello in July |
| August | 26° / 15° | 6 | 25 | 0 | 120 mm | Perfect | Monticello in August |
| September | 22° / 11° | 4 | 26 | 0 | 84 mm | Good | Monticello in September |
| October | 13° / 5° | 5 | 23 | 3 | 90 mm | Bad | Monticello in October |
| November | 4° / -2° | 4 | 18 | 8 | 51 mm | Awful | Monticello in November |
| December | -4° / -9° | 4 | 11 | 16 | 48 mm | Awful | Monticello in December |