January in Monte Carlo is the rainiest, the cloudiest, and the coldest month of the year. In January, the weather in Monte Carlo is typically warm. Average daily high temperature in January is about 11 degrees above zero. On average, Monte Carlo has 15 sunny, 13 partly cloudy, and 3 rainy days in January. The rains are usually light. January as well as February and December is considered the most uncomfortable time to visit Monte Carlo.