January in Viana do Castelo is the rainiest, the windiest, the cloudiest, and the coldest month of the year. In January, the weather in Viana do Castelo is typically warm. Average daily high temperature in January is about 12 degrees above zero. On average, Viana do Castelo has 18 rainy, 10 sunny, and 3 partly cloudy days in January. The rains are usually heavy. January as well as February, November, and December is considered the most uncomfortable time to visit Viana do Castelo.