Will Pipes Freeze in Merrimack County, NH? 80 nights a Year
Freeze nights in Merrimack County
In a normal year Merrimack County, NH gets 80 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 82% of US counties.
Risk level: Severe. The risk season runs November to April, worst in January.
It depends where the pipe is
| Pipe | Freezes near | Nights a year |
|---|---|---|
| Outdoor spigot, open crawlspace | 32°F | 172 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 80 nights |
| Insulated pipe in unheated space | 10°F | 40 nights |
| Inside the heated house | 0°F | 16 nights |
Foam-sleeving a bare pipe in unheated space takes it from 80 nights of risk to 40 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 09/29, last around 05/14. For 20°F: 11/13 to 04/04.
How cold Merrimack County nights get
Average winter (Dec-Feb) low: 15°F; the coldest month, January, averages 12°F overnight. 9 months normally bring at least one night below 32°F (Jan, Feb, Mar, Apr, May, Sep, Oct, Nov, Dec). Nights below 10°F, cold enough to freeze insulated pipe in an unheated space, come in January, February, March, November, December: 40 nights a year, and 16 nights below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 12°F | 13°F | 21°F | 31°F | 42°F | 52°F | 57°F | 55°F | 47°F | 36°F | 28°F | 19°F |
Merrimack County next to its neighbours
Sullivan County, NH, 44 km west, gets 94 nights below 20°F to Merrimack County's 80 nights. Belknap County, NH, 32 km northeast, gets 72 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Merrimack County, NH | - | 172 nights | 80 nights | 12°F |
| Belknap County, NH | 32 km northeast | 152 nights | 72 nights | 12°F |
| Hillsborough County, NH | 43 km south | 161 nights | 72 nights | 14°F |
| Sullivan County, NH | 44 km west | 185 nights | 94 nights | 9°F |
| Strafford County, NH | 52 km east | 146 nights | 63 nights | 15°F |
| Rockingham County, NH | 58 km southeast | 154 nights | 65 nights | 14°F |
| Cheshire County, NH | 62 km southwest | 169 nights | 77 nights | 11°F |
Merrimack County within NH
Merrimack County ranks 5 of 10 NH counties for nights below 20°F. The most is Coos County, NH at 110 nights, with a 6°F average winter low. The fewest is Strafford County, NH: 63 nights, winter lows near 18°F. At 436 ft, Merrimack County sits 276 ft below the state's median county elevation of 712 ft.
What to do here
- Treat it as a building fix, not a night-of routine: insulate, heat tape, seal crawlspace vents.
- An automatic leak shutoff pays for itself if one burst is avoided.
- Know where the main shutoff is before the first hard freeze.
Interior pipes have a threshold too: the four freeze points.
Where this comes from
NOAA 1991-2020 climate normals, blended from 3 nearby stations and adjusted for elevation; closest is Salisbury, NH, 8 km away (close match). A normal year, not tonight's forecast: check the forecast low for the night itself. What a "fair" or "distant" station match means is in the method guide.