January in Mendoza is the rainiest, the cloudiest, and the warmest month of the year. In January, the weather in Mendoza is typically warm. Average daily high temperature in January is about 22 degrees above zero. On average, Mendoza has 21 rainy, 7 sunny, and 3 partly cloudy days in January. The rains are usually heavy. January as well as February, March, and December is considered the most uncomfortable time to visit Mendoza.