In December, the weather in Manitowoc is typically freezing. Average daily high temperature in December is about zero. On average, Manitowoc has 9 partly cloudy, 8 sunny, 8 cloudy, 3 rainy, and 3 snowy days in December. The rains are usually moderate. December as well as February, March, April, and May is considered the most uncomfortable time to visit Manitowoc.