Will Pipes Freeze in Modoc County, CA? 70 nights a Year
Freeze nights in Modoc County
In a normal year Modoc County, CA gets 70 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 77% of US counties.
Risk level: Severe. The risk season runs October to April, worst in December.
It depends where the pipe is
| Pipe | Freezes near | Nights a year |
|---|---|---|
| Outdoor spigot, open crawlspace | 32°F | 198 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 70 nights |
| Insulated pipe in unheated space | 10°F | 19 nights |
| Inside the heated house | 0°F | 5 nights |
Foam-sleeving a bare pipe in unheated space takes it from 70 nights of risk to 19 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 09/12, last around 06/03. For 20°F: 10/23 to 04/05.
How cold Modoc County nights get
Average winter (Dec-Feb) low: 21°F; the coldest month, January, averages 21°F overnight. 11 months normally bring at least one night below 32°F (Jan, Feb, Mar, Apr, May, Jun, Aug, 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: 19 nights a year, and 5 nights below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 21°F | 23°F | 27°F | 30°F | 37°F | 42°F | 47°F | 44°F | 38°F | 30°F | 24°F | 21°F |
Modoc County next to its neighbours
Klamath County, OR, 143 km northwest, gets 73 nights below 20°F to Modoc County's 70 nights. Lassen County, CA, 98 km south, gets 49 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Modoc County, CA | - | 198 nights | 70 nights | 21°F |
| Lassen County, CA | 98 km south | 176 nights | 49 nights | 22°F |
| Washoe County, NV | 130 km southeast | 164 nights | 54 nights | 21°F |
| Lake County, OR | 136 km north | 170 nights | 58 nights | 22°F |
| Klamath County, OR | 143 km northwest | 222 nights | 73 nights | 18°F |
| Shasta County, CA | 144 km southwest | 17 nights | under 1 night | 39°F |
| Siskiyou County, CA | 151 km west | 139 nights | 26 nights | 27°F |
Modoc County within CA
Modoc County ranks 3 of 58 CA counties for nights below 20°F. The most is Mono County, CA at 130 nights, with a 13°F average winter low. The fewest is Orange County, CA: none, winter lows near 46°F. At 5,063 ft, Modoc County sits 3,765 ft above the state's median county elevation of 1,298 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 Alturas Municipal Airport, CA, 17 km away (fair match). A normal year, not tonight's forecast: check the forecast low for the night itself. How a county figure is built from stations: how the numbers are made.