Fairfax County Climate
Fairfax County, Virginia
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
54.9°F
Annual Precip
43.4"
Annual Snowfall
19.8"
Extreme Heat Days
23
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
7b
Minimum winter temperature range for plant survival
3,679
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Fairfax County
Climate Verdict
Fairfax County has a mild, with an average annual temperature of 54.9°F, moderately wet with 43.4 inches of annual precipitation, occasional hot days — 23.05 per year above 90°F, light snow averaging 19.8 inches per year. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are cold, with January averaging 33.4°F. summers are warm — July averages 76.2°F. The 43°F seasonal variation provides noticeable but manageable change.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for Fairfax County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
Fairfax County closely matches the Virginia statewide average temperature of 56.2°F, it is somewhat drier than average for Virginia.
Climate Profile
About Fairfax County Weather
Predictable Mid-Atlantic Weather
Fairfax County’s 54.9°F annual average temperature sits right near the national median. It experiences a classic four-season climate typical of the Mid-Atlantic region.
Cooler Than the State Average
The county is exactly one degree cooler than the Virginia state average of 55.9°F. This difference reflects the slightly harsher winters found in Northern Virginia.
Consistent Regional Precipitation
Fairfax receives 43.4 inches of annual precipitation, slightly less than the state average of 45.7 inches. Its 19.8 inches of annual snow is typical for the Northern Virginia corridor.
Balanced Seasonal Extremes
Residents face 23 days of extreme heat over 90°F each summer. Winters are cold but manageable, with an average December-February temperature of 35.5°F.
Ready for Every Season
You will need a full wardrobe ranging from heavy parkas for the 19.8 inches of snow to light clothing for the 23 heat days. A balanced HVAC system is vital for year-round comfort.
Frequently Asked Questions
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Data sources: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020. Forecast and alert data from National Weather Service API. Air quality data from Open-Meteo.
Climate normals are 30-year averages of weather variables. Station data is aggregated to county level. Forecasts and alerts are fetched live and may change frequently. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.