Will Pipes Freeze in Fairfax County, VA? 24 nights a Year
Freeze nights in Fairfax County
In a normal year Fairfax County, VA gets 24 nights at or below 20°F, the point where bare pipes in a garage, attic or outside wall start to freeze. That is more than 40% of US counties.
Risk level: Regular. The risk season runs November to March, worst in January.
It depends where the pipe is
| Pipe | Freezes near | Nights a year |
|---|---|---|
| Outdoor spigot, open crawlspace | 32°F | 99 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 24 nights |
| Insulated pipe in unheated space | 10°F | 4 nights |
| Inside the heated house | 0°F | under 1 night |
Foam-sleeving a bare pipe in unheated space takes it from 24 nights of risk to 4 nights. A 12 ft heat-tape kit runs $17 to $37; an average burst-pipe repair is about $500.
Month by month
Nights at or below 20°F in a normal year.
First 32°F night is usually around 10/29, last around 04/14. For 20°F: 12/06 to 03/09.
How cold Fairfax County nights get
Average winter (Dec-Feb) low: 26°F; the coldest month, January, averages 24°F overnight. 7 months normally bring at least one night below 32°F (Jan, Feb, Mar, Apr, Oct, Nov, Dec). Nights below 10°F, cold enough to freeze insulated pipe in an unheated space, come in January, February: 4 nights a year, and under 1 night below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 24°F | 25°F | 32°F | 42°F | 52°F | 61°F | 67°F | 65°F | 57°F | 45°F | 35°F | 29°F |
Fairfax County next to its neighbours
Fairfax city, VA, 3 km northwest, gets 24 nights below 20°F to Fairfax County's 24 nights. Falls Church city, VA, 10 km northeast, gets 21 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Fairfax County, VA | - | 99 nights | 24 nights | 24°F |
| Fairfax city, VA | 3 km northwest | 100 nights | 24 nights | 24°F |
| Falls Church city, VA | 10 km northeast | 92 nights | 21 nights | 25°F |
| Arlington County, VA | 16 km east | 83 nights | 18 nights | 27°F |
| Manassas Park city, VA | 16 km southwest | 95 nights | 24 nights | 24°F |
| Alexandria city, VA | 16 km east | 76 nights | 15 nights | 28°F |
| Manassas city, VA | 20 km southwest | 94 nights | 24 nights | 24°F |
Fairfax County within VA
Fairfax County ranks 65 of 133 VA counties for nights below 20°F. The most is Highland County, VA at 62 nights, with a 20°F average winter low. The fewest is Norfolk city, VA: 4 nights, winter lows near 35°F. At 371 ft, Fairfax County sits 77 ft below the state's median county elevation of 448 ft.
What to do here
- Insulate every pipe in unheated space before the season starts.
- Heat tape on the runs you cannot insulate well.
- Shut off and drain outdoor spigots for the season.
Why 20°F is the line for a garage pipe: how cold before pipes freeze.
Where this comes from
NOAA 1991-2020 climate normals, blended from 3 nearby stations and adjusted for elevation; closest is Vienna, VA, 7 km away (close match). A normal year, not tonight's forecast: check the forecast low for the night itself. Why elevation is part of the blend: how county numbers are made.