Fairfax County, Virginia, gets 42 inches of rain per year. The US average is 37. Snowfall is 12 inches. The average US city gets 25 inches of snow per year. The number of days with any measurable precipitation is 109.
On average, there are 199 sunny days per year in Fairfax County, Virginia. The July high is around 88 degrees. The January low is 24. Our comfort index, which is based on humidity during the hot months, is a 41 out of 100, where higher is more comfortable. The US average on the comfort index is 44.