In December, the weather in Niagara Falls is typically cold. Average daily high temperature in December is about 3 degrees above zero. On average, Niagara Falls has 12 cloudy, 8 rainy, 6 partly cloudy, 3 sunny, and 2 snowy days in December. The rains are usually heavy. December as well as January, February, March, and April is considered the most uncomfortable time to visit Niagara Falls.