Click on a day for an hourly weather forecast
The temperatures in Viterbo in September are comfortable with low of 16°C and and high up to 26°C.
You can expect about 3 to 8 days of rain in Viterbo 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 Viterbo in September 2026.
If you’re planning to visit Viterbo in the near future, we highly recommend that you review the 14 day weather forecast for Viterbo before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 10° / 3° | 5 | 25 | 1 | 95 mm | Ok | Viterbo in January |
| February | 11° / 4° | 5 | 22 | 2 | 92 mm | Bad | Viterbo in February |
| March | 14° / 5° | 6 | 25 | 1 | 85 mm | Good | Viterbo in March |
| April | 18° / 8° | 4 | 26 | 0 | 65 mm | Good | Viterbo in April |
| May | 21° / 11° | 7 | 24 | 0 | 96 mm | Ok | Viterbo in May |
| June | 27° / 15° | 5 | 25 | 0 | 90 mm | Perfect | Viterbo in June |
| July | 31° / 19° | 3 | 28 | 0 | 76 mm | Good | Viterbo in July |
| August | 31° / 19° | 3 | 28 | 0 | 48 mm | Good | Viterbo in August |
| September | 26° / 16° | 4 | 26 | 0 | 106 mm | Perfect | Viterbo in September |
| October | 21° / 12° | 4 | 27 | 0 | 100 mm | Good | Viterbo in October |
| November | 15° / 8° | 7 | 23 | 0 | 151 mm | Ok | Viterbo in November |
| December | 11° / 5° | 6 | 25 | 1 | 91 mm | Ok | Viterbo in December |