The average temperature of Fairfax County is 54.77°F, which is about the same as the Virginia average temperature of 55.54°F and is about the same as the national average temperature of 54.45°F.
The Heating Cost Index and the Cooling Cost Index are indicators of the relative heating and cooling cost of an area. They were calculated based on the average temperate and duration of the hot and cold days for the area. Please note, the actual heating cost and cooling cost are also dependent on other factors specific to individual residences such as the size of the house, the insulation condition, and the equipment efficiency, etc.
Average Number of Days with 0.1 Inch or More Precipitation in a Year (this gives an indication of the number of days in a year that it is useful to have an umbrella), #89
* The temperature, snow fall, and precipitation information on this page were calculated from the historical data of 18,000+ U.S weather stations for the period of time from 1980 to 2010. The humidity and wind speed information were calculated from data from 15,000 worldwide stations for the period of time from 1980 to 2010.
