Will Pipes Freeze in Calvert County, MD? 16 nights a Year
Freeze nights in Calvert County
In a normal year Calvert County, MD gets 16 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 32% of US counties.
Risk level: Regular. The risk season runs December to March, worst in January.
It depends where the pipe is
| Pipe | Freezes near | Nights a year |
|---|---|---|
| Outdoor spigot, open crawlspace | 32°F | 82 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 16 nights |
| Insulated pipe in unheated space | 10°F | 3 nights |
| Inside the heated house | 0°F | under 1 night |
Foam-sleeving a bare pipe in unheated space takes it from 16 nights of risk to 3 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 04/17. For 20°F: 12/03 to 03/09.
How cold Calvert County nights get
Average winter (Dec-Feb) low: 29°F; the coldest month, January, averages 27°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: 3 nights a year, and under 1 night below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 27°F | 28°F | 35°F | 45°F | 55°F | 64°F | 69°F | 67°F | 61°F | 49°F | 39°F | 31°F |
Calvert County next to its neighbours
Charles County, MD, 43 km west, gets 17 nights below 20°F to Calvert County's 16 nights. St. Mary's County, MD, 33 km south, gets 10 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Calvert County, MD | - | 82 nights | 16 nights | 27°F |
| St. Mary's County, MD | 33 km south | 65 nights | 10 nights | 30°F |
| Talbot County, MD | 40 km northeast | 69 nights | 12 nights | 29°F |
| Charles County, MD | 43 km west | 86 nights | 17 nights | 27°F |
| Dorchester County, MD | 43 km east | 77 nights | 14 nights | 28°F |
| Prince George's County, MD | 44 km northwest | 99 nights | 26 nights | 25°F |
| Westmoreland County, VA | 52 km southwest | 74 nights | 12 nights | 29°F |
Calvert County within MD
Calvert County ranks 17 of 24 MD counties for nights below 20°F. The most is Garrett County, MD at 57 nights, with a 20°F average winter low. The fewest is Baltimore city, MD: 10 nights, winter lows near 32°F. At 138 ft, Calvert County sits close to the state's median county elevation of 138 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 Mechanicsville (5 mi NE), MD, 17 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.