In December, the weather in Santiago de Compostela is typically warm. Average daily high temperature in December is about 11 degrees above zero. On average, Santiago de Compostela has 17 rainy, 7 sunny, 4 partly cloudy, and 3 cloudy days in December. The rains are usually heavy. December as well as January, February, March, and November is considered the most uncomfortable time to visit Santiago de Compostela.