January in Las Vegas is the cloudiest month of the year. In January, the weather in Las Vegas is typically warm. Average daily high temperature in January is about 12 degrees above zero. On average, Las Vegas has 19 sunny, 10 partly cloudy, 1 rainy, and 1 cloudy day in January. The rains are usually light. January as well as June, July, August, and December is considered the most uncomfortable time to visit Las Vegas.