Will Pipes Freeze in Prince William County, VA? 24 nights a Year
Freeze nights in Prince William County
In a normal year Prince William 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 | 95 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 | none |
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 10/27, last around 04/12. For 20°F: 12/01 to 03/09.
How cold Prince William 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 none below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 24°F | 26°F | 32°F | 43°F | 54°F | 63°F | 69°F | 66°F | 58°F | 46°F | 35°F | 29°F |
Prince William County next to its neighbours
Fauquier County, VA, 30 km west, gets 28 nights below 20°F to Prince William County's 24 nights. Stafford County, VA, 31 km south, gets 19 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Prince William County, VA | - | 95 nights | 24 nights | 24°F |
| Manassas city, VA | 5 km north | 94 nights | 24 nights | 24°F |
| Manassas Park city, VA | 8 km northeast | 95 nights | 24 nights | 24°F |
| Fairfax County, VA | 23 km northeast | 99 nights | 24 nights | 24°F |
| Fairfax city, VA | 23 km northeast | 100 nights | 24 nights | 24°F |
| Fauquier County, VA | 30 km west | 102 nights | 28 nights | 25°F |
| Stafford County, VA | 31 km south | 91 nights | 19 nights | 27°F |
Prince William County within VA
Prince William County ranks 62 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 214 ft, Prince William County sits 234 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.
What insulating actually removes here, and when heat tape is needed: insulate or heat tape?.
Where this comes from
NOAA 1991-2020 climate normals, blended from 3 nearby stations and adjusted for elevation; closest is Manassas, VA, 4 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.