December in Rio Gallegos is the rainiest month of the year. In December, the weather in Rio Gallegos is typically warm. Average daily high temperature in December is about 14 degrees above zero. On average, Rio Gallegos has 16 rainy, 8 cloudy, 4 partly cloudy, and 3 sunny days in December. The rains are usually light. December as well as April, May, June, and July is considered the most uncomfortable time to visit Rio Gallegos.