Grass Valley, California, gets 51 inches of rain per year. The US average is 39. Snowfall is 17 inches. The average US city gets 26 inches of snow per year. The number of days with any measurable precipitation is 82.
On average, there are 243 sunny days per year in Grass Valley, California. The July high is around 87 degrees. The January low is 35. Sperling's comfort index for Grass Valley is a 79 out of 100, where a higher score indicates a more comfortable year-around climate. The US average for the comfort index is 54. Our index is based on the total number of days annually within the comfort range of 70-80 degrees, and we also applied a penalty for days of excessive humidity.