January in Norrtalje is the snowiest, the cloudiest, and the most freezing month of the year. In January, the weather in Norrtalje is typically freezing. Average daily high temperature in January is about 1 degree below zero. On average, Norrtalje has 15 cloudy, 11 snowy, 2 rainy, 2 sunny, and 1 partly cloudy day in January. The snowfalls are usually light.