Will Pipes Freeze in Petersburg Borough, AK? 20 nights a Year
Freeze nights in Petersburg Borough
In a normal year Petersburg Borough, AK gets 20 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 36% 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 | 99 nights |
| Bare pipe in garage, attic or outside wall | 20°F | 20 nights |
| Insulated pipe in unheated space | 10°F | 5 nights |
| Inside the heated house | 0°F | under 1 night |
Foam-sleeving a bare pipe in unheated space takes it from 20 nights of risk to 5 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 10/17, last around 04/29. For 20°F: 12/01 to 03/07.
How cold Petersburg Borough nights get
Average winter (Dec-Feb) low: 29°F; the coldest month, January, averages 28°F overnight. 8 months normally bring at least one night below 32°F (Jan, Feb, Mar, Apr, May, Oct, Nov, Dec). Nights below 10°F, cold enough to freeze insulated pipe in an unheated space, come in January, February, March, December: 5 nights a year, and under 1 night below zero.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 28°F | 29°F | 31°F | 36°F | 42°F | 48°F | 51°F | 50°F | 46°F | 40°F | 33°F | 30°F |
Petersburg Borough next to its neighbours
Juneau City and Borough, AK, 156 km northwest, gets 41 nights below 20°F to Petersburg Borough's 20 nights. Wrangell City and Borough, AK, 120 km southeast, gets 14 nights.
| County | Distance | Below 32°F | Below 20°F | Jan low |
|---|---|---|---|---|
| Petersburg Borough, AK | - | 99 nights | 20 nights | 28°F |
| Wrangell City and Borough, AK | 120 km southeast | 92 nights | 14 nights | 29°F |
| Sitka City and Borough, AK | 143 km west | 96 nights | 11 nights | 30°F |
| Juneau City and Borough, AK | 156 km northwest | 144 nights | 41 nights | 21°F |
| Prince of Wales-Hyder Census Area, AK | 159 km south | 91 nights | 12 nights | 31°F |
| Ketchikan Gateway Borough, AK | 219 km southeast | 75 nights | 10 nights | 32°F |
| Hoonah-Angoon Census Area, AK | 223 km northwest | 154 nights | 37 nights | 24°F |
Petersburg Borough within AK
Petersburg Borough ranks 22 of 26 AK counties for nights below 20°F. The most is Southeast Fairbanks Census Area, AK at 192 nights, with a -19°F average winter low. The fewest is Ketchikan Gateway Borough, AK: 10 nights, winter lows near 32°F. At 3,153 ft, Petersburg Borough sits 2,331 ft above the state's median county elevation of 822 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.
What insulating actually removes here, and when heat tape is needed: insulate or heat tape?.
Where this comes from
NOAA 1991-2020 climate normals, blended from 3 nearby stations and adjusted for elevation; closest is Petersburg 1, AK, 34 km away (distant 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.