Will Pipes Freeze in San Diego County, CA? 4 nights a Year
Freeze nights in San Diego County
In a normal year San Diego County, CA gets 4 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 14% of US counties.
Risk level: Occasional. The risk season runs December to February, worst in December.
It depends where the pipe is
| Pipe | Freezes near | Nights a year |
|---|---|---|
| Outdoor spigot, open crawlspace | 32°F | 57 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 4 nights |
| Insulated pipe in unheated space | 10°F | under 1 night |
| Inside the heated house | 0°F | none |
Foam-sleeving a bare pipe in unheated space takes it from 4 nights of risk to under 1 night. 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 10/26, last around 04/18. For 20°F: 12/16 to 01/05.
How cold San Diego County nights get
Average winter (Dec-Feb) low: 36°F; the coldest month, December, averages 35°F overnight. 8 months normally bring at least one night below 32°F (Jan, Feb, Mar, Apr, May, Oct, Nov, Dec).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 36°F | 37°F | 39°F | 42°F | 47°F | 50°F | 56°F | 58°F | 54°F | 46°F | 40°F | 35°F |
San Diego County next to its neighbours
Riverside County, CA, 106 km northeast, gets under 1 night.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| San Diego County, CA | - | 57 nights | 4 nights | 36°F |
| Riverside County, CA | 106 km northeast | 14 nights | under 1 night | 40°F |
| Orange County, CA | 118 km northwest | 1 night | none | 46°F |
| Imperial County, CA | 132 km east | 5 nights | none | 42°F |
| Los Angeles County, CA | 190 km northwest | under 1 night | none | 45°F |
| San Bernardino County, CA | 211 km north | 28 nights | under 1 night | 36°F |
| Ventura County, CA | 264 km northwest | 23 nights | under 1 night | 37°F |
San Diego County within CA
San Diego County ranks 14 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 2,425 ft, San Diego County sits 1,127 ft above the state's median county elevation of 1,298 ft.
What to do here
- Keep a night-of routine: drip, open cabinets, keep the heat at 55F or above.
- Foam-sleeve any pipe in the garage or crawlspace once; it is cheap and lasts years.
Few hard nights means pipes are rarely built for them; see freezes in warm places.
Where this comes from
NOAA 1991-2020 climate normals, blended from 3 nearby stations and adjusted for elevation; closest is Henshaw Dam, CA, 24 km away (fair 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.