In March, the weather in Calw is typically cold. Average daily high temperature in March is about 8 degrees above zero. On average, Calw has 11 rainy, 8 cloudy, 7 sunny, 4 partly cloudy, and 1 snowy day in March. The rains are usually heavy. March as well as January, February, April, and May is considered the most uncomfortable time to visit Calw.