January in Greven is the rainiest and the coldest month of the year. In January, the weather in Greven is typically cold. Average daily high temperature in January is about 4 degrees above zero. On average, Greven has 21 rainy, 6 cloudy, 3 sunny, and 1 partly cloudy day in January. The rains are usually moderate. January as well as February, November, and December is considered the most uncomfortable time to visit Greven.