Click on a day for an hourly weather forecast
The temperatures in Viana do Castelo in August are comfortable with low of 17°C and and high up to 24°C.
You can expect a few rainy days in Viana do Castelo during August, but usually the weather is comfortable in August.
Our weather forecast can give you a great sense of what weather to expect in Viana do Castelo in August 2025.
If you’re planning to visit Viana do Castelo in the near future, we highly recommend that you review the 14 day weather forecast for Viana do Castelo before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 13° / 8° | 9 | 22 | 0 | 77 mm | Bad | Viana do Castelo in January |
| February | 14° / 8° | 7 | 21 | 0 | 57 mm | Ok | Viana do Castelo in February |
| March | 15° / 9° | 8 | 23 | 0 | 59 mm | Ok | Viana do Castelo in March |
| April | 17° / 10° | 7 | 23 | 0 | 49 mm | Good | Viana do Castelo in April |
| May | 19° / 12° | 5 | 26 | 0 | 34 mm | Good | Viana do Castelo in May |
| June | 21° / 15° | 3 | 27 | 0 | 17 mm | Good | Viana do Castelo in June |
| July | 23° / 16° | 1 | 30 | 0 | 7 mm | Perfect | Viana do Castelo in July |
| August | 24° / 17° | 1 | 30 | 0 | 8 mm | Perfect | Viana do Castelo in August |
| September | 23° / 16° | 3 | 27 | 0 | 26 mm | Perfect | Viana do Castelo in September |
| October | 20° / 14° | 9 | 22 | 0 | 90 mm | Ok | Viana do Castelo in October |
| November | 16° / 11° | 10 | 20 | 0 | 79 mm | Ok | Viana do Castelo in November |
| December | 14° / 9° | 10 | 21 | 0 | 86 mm | Ok | Viana do Castelo in December |