Key takeaways
- Boise gets cold enough to freeze pipes every year. From 2014 through 2023, the yearly low was 16°F or colder every year, and 10°F or colder in nine of those 10 years.
- Pipes can freeze around 20°F. University of Illinois field tests found that uninsulated pipes in an unheated attic began to freeze when it was about 20°F outside.
- Normal winter nights come close. Boise’s normal low is 25°F in December and 26°F in January, so it doesn’t take a record cold snap to put pipes at risk.
Words you’ll see
- Yearly low
- The coldest temperature recorded at the weather station in a given year.
- Normal low
- The average low temperature for a month over a 30-year period (here, 1991 to 2020).
- Main water shutoff
- The valve that stops all water coming into your home.
- Hose bib
- An outdoor faucet where you attach a garden hose.
- Crawl space
- The short, unheated space under some houses where pipes often run.
On this page
How cold does Boise get?
The table below shows Boise’s coldest temperature for each year from 2014 through 2023, from NOAA weather station records (Boise Airport). 2023 is the most recent year in this data set.
What the numbers show:
- Every year from 2014 through 2023 reached 16°F or colder.
- Nine of those 10 years reached 10°F or colder. The only exception was 2020, at 16°F.
- The coldest reading of the decade was −11°F on Jan. 6, 2017.
- All 10 of these yearly lows came between November and February.
Boise’s normal low, based on 1991 to 2020 averages, is 25°F in December and 26°F in January. That’s only 5 to 6 degrees above the 20°F point where pipes in cold spots can start to freeze.
Why 20 degrees matters
Water freezes at 32°F, but pipes inside a house are usually protected by some heat. So the real question is how cold it has to get outside before pipes in the coldest parts of a home freeze.
Field tests by the University of Illinois Building Research Council found that freezing began when the outside temperature fell to 20°F or below. These were uninsulated pipes in an unheated attic. Multnomah County, Oregon, for example, cites that research in its frozen pipe guide.
Which pipes are most at risk in Boise homes
The pipes most likely to freeze are the ones in spaces that don’t get much heat. In Boise-area homes, check these spots first:
- Crawl spaces. In homes with a crawl space, water lines often run under the floor, where cold air can get in through foundation vents.
- Attics. Uninsulated pipes in an unheated attic match the setup in the University of Illinois tests.
- Garages. Water lines to a laundry area or water heater in the garage can freeze if the door is left open.
- Outside walls. Pipes under kitchen and bathroom sinks on outside walls, especially where there’s little insulation behind them.
- Outdoor faucets and hoses. Hose bibs and anything still attached to them are especially exposed to freezing.
Our guide to a burst pipe in the crawl space covers how to spot trouble under the floor.
Before a cold night: simple steps
The American Red Cross recommends these steps when very cold weather is on the way:
- 1
Take care of outdoor faucets
Disconnect, drain, and store garden hoses. If an outdoor faucet has a shutoff valve inside the house, close that valve, then open the outdoor faucet and leave it open so leftover water can drain.
- 2
Let warm air reach the pipes
First, move cleaners and chemicals out of reach of kids and pets. Then open kitchen and bathroom cabinet doors, especially on outside walls.
- 3
Let a faucet drip
When it’s very cold, let cold water drip from a faucet fed by exposed pipes. Even a trickle of moving water helps keep pipes from freezing.
- 4
Keep the heat steady
Keep the thermostat at the same temperature day and night. If you’re going away, leave the heat on and set it no lower than 55°F.
- 5
Keep the garage door closed
If water lines run through the garage, keep the door closed as much as you can.
If a pipe freezes
If you turn on a faucet and only a trickle comes out, or nothing at all, a pipe may be frozen. Keep the faucet open so water can flow once it starts to thaw.
If a pipe bursts: what to do
A burst pipe can soak floors, walls, and ceilings fast. These steps can limit the damage and help with an insurance claim:
- 1
Shut off the main water valve
Stay safe first: if water is near outlets, cords, or your electrical panel, don’t walk through it. Turn off power only if you can reach the breaker panel from dry ground. Then shut off the main valve to stop more water from coming in.
- 2
Take photos and video
Record the damage before you move or throw anything away. Keep receipts for anything you pay for, like emergency repairs or fans.
- 3
Call your insurance company
Report the claim promptly, and ask about your deductible and any deadlines. Our Idaho water damage claim checklist is free to print and walks you through it.
- 4
Get the water dried out
A plumber fixes the pipe. A water damage restoration company handles drying out your home and checking for hidden moisture in walls and floors.
If a claim stalls, the Idaho Department of Insurance offers free consumer help at 208-334-4250 or 800-721-3272. For more detail, see our guide to a frozen or burst pipe in Boise.
For reporters and neighborhood groups
You’re welcome to cite or share this page. Please credit Boise Water Damage Help (boisewaterdamageline.com), run by BluePeak Media, and link back to this page.
- Temperature data: NOAA National Centers for Environmental Information, Global Summary of the Year, Boise Airport station, as compiled by Current Results.
- Normal lows: NOAA 1991 to 2020 normals, as compiled by Current Results.
- 20°F pipe-freezing threshold: University of Illinois Building Research Council field tests, as cited by Multnomah County, Oregon.
- Prevention and thawing tips: American Red Cross.
We’ll add newer years to the table when they become available in the NOAA data.
Frequently asked questions
At what temperature do pipes freeze in Boise?
There’s no single number, but field tests by the University of Illinois found that uninsulated pipes in an unheated attic began to freeze when it was about 20°F outside. In general, wind and air leaks can freeze pipes at warmer temperatures.
How cold does it get in Boise in winter?
From 2014 through 2023, Boise’s coldest temperature each year ranged from 16°F down to −11°F, based on NOAA records. The normal low is 25°F in December and 26°F in January.
Should I let my faucets drip in Boise?
On very cold nights, yes, for faucets fed by pipes in unheated spaces like crawl spaces and garages, or along outside walls. The American Red Cross says even a trickle of moving water helps keep pipes from freezing.
A burst pipe is stressful, but you don’t have to sort it out alone.
If a pipe has already burst and water got into your floors, walls, or ceiling, call and we’ll try to connect you with an independent water damage provider near you. If the pipe is only frozen, a licensed plumber is the right call.
Read next
Related guides
Sources (checked November 10, 2026)
- NOAA NCEI Global Summary of the Year, via Current Results, “Boise - Lowest Temperature for Each Year”: https://www.currentresults.com/Yearly-Weather/USA/ID/Boise/extreme-annual-boise-low-temperature.php
- NOAA 1991 to 2020 normals, via Current Results, “Boise Temperatures: Averages by Month”: https://www.currentresults.com/Weather/Idaho/Places/boise-temperatures-by-month-average.php
- Multnomah County, Oregon, “Freezing and Bursting Pipes” (cites University of Illinois Building Research Council): https://multco.us/file/46297/download
- American Red Cross, “Frozen Pipes”: https://www.redcross.org/get-help/how-to-prepare-for-emergencies/types-of-emergencies/winter-storm/frozen-pipes.html
- Idaho Department of Insurance, “Home & Renters Claims”: https://doi.idaho.gov/consumers/home-renters-insurance/home-renters-claims/
Update log
- November 10, 2026: First published.