In December, the weather in San Miguel de Allende is typically warm. Average daily high temperature in December is about 23 degrees above zero. On average, San Miguel de Allende has 18 sunny, 9 partly cloudy, 3 cloudy, and 1 rainy day in December. The rains are usually light. December as well as January, February, and November is considered the most comfortable time to visit San Miguel de Allende.