How often it gets cold enough to freeze pipes, city by city

Frozen pipe questions, answered from the data

At what temperature do pipes freeze?

Water freezes at 32°F, but a pipe inside a house is sheltered, so it takes a colder night.

Field tests by the University of Illinois Building Research Council, cited by Multnomah County's freeze guidance, found uninsulated pipes in an unheated attic began freezing when the outdoor temperature fell to 20°F, and treat 20°F as the alert threshold where freezing weather is the exception. Wind and drafts can freeze exposed pipes at higher temperatures.

Which U.S. cities have the most nights cold enough to freeze pipes?

In NOAA's 1991–2020 normals, the coldest cities in our 509-city dataset average more than 100 nights a year at or below 20°F (North Dakota has a median of 109 such nights across its cities). Among cities over 500,000 people, Denver leads with 61.5 nights a year, followed by Milwaukee (52.4) and Chicago (41.2).

Do pipes freeze in the South?

YesThough rarely. 118 cities in the dataset average between half a night and ten nights a year at or below 20°F, a median of 3.4; Dallas averages 1.6 and Atlanta 4.3.

The Building Research Council work set 20°F as the alert point for these places because homes there are less likely to have pipes protected for cold.

When should I winterize my pipes?

Before your city's first hard freeze. Across the dataset, the median first 20°F night is Nov 17 in the coldest group of cities, Dec 3 in the middle group and Jan 1 where hard freezes are occasional; Chicago's median first 20°F night is Nov 29. The table below gives the date for each city.

Can I use this data on my website?

YesThe dataset is published under CC BY 4.0: use it, chart it or republish it with a link to this page as the source. The full table is available as CSV and JSON.

Who do I call right now for water damage?

Call (888) 840-6512. The line is answered 24 hours a day, seven days a week, and connects you with an IICRC-certified water damage restoration company that serves your area. A recorded menu picks up first: choose water damage or mold, key in your 5-digit ZIP code, and hold through the short silence while the call is passed to the company.

Describe what you can see — where the water is coming from, how long it has been there, and whether it smells — the more specific you are, the faster the right company is on the line. If the source is a pipe or an appliance, shut the main water valve first. Have four things ready and the call goes quickly: the address, when the water started, what is wet now, and whether you have filed an insurance claim.

Still not sure which of these is your situation? (888) 840-6512 · toll-free · answered 24/7