Climate in Viana do Castelo
(Portugal)

The number of hours of sunshine refers to the time when the sun is actually visible. That is, without any obstruction of visibility by clouds, fog or mountains. With 10 hours per day, July is the sunniest month in the region of Viana do Castelo. In December the sun shines the shortest.

A rainy day is a day on which at least an amount of 0.1 mm precipitation (=0.1 liter) per square meter falls. This can be rain, snow, hail or even dew. So it does not have to rain the whole day. With 15 rainy days, January offers the most number of rainy days, and in July the least.

The amount of precipitation is measured in millimeters per square meter. Thus, at 2 mm/day, 2 liters of water fall on one square meter within 24 hours. With only 1.2 mm, the least rain falls in July. October, on the other hand, has the most rain.