Will Pipes Freeze in San Juan County, WA? 2 nights a Year
Freeze nights in San Juan County
In a normal year San Juan County, WA gets 2 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 9% of US counties.
Risk level: Rare. The risk season runs December to January, worst in January.
It depends where the pipe is
| Pipe | Freezes near | Nights a year |
|---|---|---|
| Outdoor spigot, open crawlspace | 32°F | 39 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 2 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 2 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 11/10, last around 03/26. For 20°F: 12/24 to 01/01.
How cold San Juan County nights get
Average winter (Dec-Feb) low: 37°F; the coldest month, February, averages 37°F overnight. 7 months normally bring at least one night below 32°F (Jan, Feb, Mar, Apr, Oct, Nov, Dec).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 37°F | 37°F | 39°F | 41°F | 45°F | 49°F | 51°F | 51°F | 48°F | 44°F | 40°F | 37°F |
San Juan County next to its neighbours
Skagit County, WA, 95 km east, gets 7 nights below 20°F to San Juan County's 2 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| San Juan County, WA | - | 39 nights | 2 nights | 37°F |
| Island County, WA | 50 km southeast | 28 nights | 1 night | 37°F |
| Clallam County, WA | 73 km southwest | 62 nights | 2 nights | 33°F |
| Jefferson County, WA | 84 km south | 61 nights | 2 nights | 34°F |
| Skagit County, WA | 95 km east | 82 nights | 7 nights | 31°F |
| Whatcom County, WA | 100 km east | 73 nights | 6 nights | 31°F |
| Kitsap County, WA | 102 km south | 46 nights | 2 nights | 35°F |
San Juan County within WA
San Juan County ranks 36 of 39 WA counties for nights below 20°F. The most is Ferry County, WA at 62 nights, with a 18°F average winter low. The fewest is Island County, WA: 1 night, winter lows near 37°F. At 194 ft, San Juan County sits 1,426 ft below the state's median county elevation of 1,620 ft.
What to do here
- Watch the forecast for a sub-threshold night.
- That night: drip the faucet on an outside wall, open the sink cabinet.
A few nights a year catches houses that were never built for it: pipes in places that rarely freeze.
Where this comes from
NOAA 1991-2020 climate normals, blended from 3 nearby stations and adjusted for elevation; closest is Friday Harbor Airport, WA, 6 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.