Will Pipes Freeze in St. Louis city, MO? 26 nights a Year
Freeze nights in St. Louis city
In a normal year St. Louis city, MO gets 26 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 42% of US counties.
Risk level: Regular. The risk season runs November to March, worst in January.
It depends where the pipe is
| Pipe | Freezes near | Nights a year |
|---|---|---|
| Outdoor spigot, open crawlspace | 32°F | 83 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 26 nights |
| Insulated pipe in unheated space | 10°F | 7 nights |
| Inside the heated house | 0°F | under 1 night |
Foam-sleeving a bare pipe in unheated space takes it from 26 nights of risk to 7 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 11/04, last around 04/01. For 20°F: 12/06 to 03/02.
How cold St. Louis city nights get
Average winter (Dec-Feb) low: 27°F; the coldest month, January, averages 24°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, December: 7 nights a year, and under 1 night below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 24°F | 28°F | 37°F | 48°F | 58°F | 67°F | 71°F | 69°F | 61°F | 49°F | 38°F | 30°F |
St. Louis city next to its neighbours
St. Louis County, MO, 18 km west, gets 31 nights below 20°F to St. Louis city's 26 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| St. Louis city, MO | - | 83 nights | 26 nights | 24°F |
| St. Louis County, MO | 18 km west | 93 nights | 31 nights | 23°F |
| St. Clair County, IL | 33 km southeast | 94 nights | 28 nights | 24°F |
| Madison County, IL | 37 km northeast | 86 nights | 28 nights | 23°F |
| Monroe County, IL | 40 km south | 102 nights | 33 nights | 23°F |
| St. Charles County, MO | 41 km northwest | 104 nights | 37 nights | 21°F |
| Jefferson County, MO | 49 km southwest | 104 nights | 34 nights | 22°F |
St. Louis city within MO
St. Louis city ranks 107 of 115 MO counties for nights below 20°F. The most is Caldwell County, MO at 65 nights, with a 19°F average winter low. The fewest is Pemiscot County, MO: 14 nights, winter lows near 31°F. At 467 ft, St. Louis city sits 375 ft below the state's median county elevation of 842 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.
Why 20°F is the line for a garage pipe: how cold before pipes freeze.
Where this comes from
NOAA 1991-2020 climate normals, blended from 3 nearby stations and adjusted for elevation; closest is St Louis Sci Ctr, MO, 2 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.