FrostList

When to Prevent Frozen Pipes in Seattle, WA

ON TRACK129 days until first freezing night (32°F)Nov 17

Pipe-risk season in Seattle opens with the first 32°F night, which averages November 17 and has come as early as November 1; watch for lows in the low 20s. Plan for the early end: the one-in-ten date lands about 20 days before the median.

OUTLOOK

Typical first first freezing night (32°F) near Nov 17; local deadline about Nov 1. The live 10-day outlook loads here.

Local freeze dates for Seattle

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Nov 1Nov 17Dec 6
28°F (hard freeze)Nov 12Dec 2Dec 30
24°F (severe)Nov 21Dec 14Jan 29

NOAA station: Seattle Boeing Fld · 5.4 mi away · 20 ft elevation.

Numbers for Seattle come from Seattle Boeing Fld, 5.4 miles away at 20 feet, where the medians fall 32°F by Nov 17, 28°F by Dec 2, 24°F by Dec 14. Year to year the 28°F date has ranged from Nov 12 to Dec 30 — about 48 days apart. Spring's last 32°F freeze clears around Mar 13. Snowfall averages 4 inches a year, first reaching an inch near December.

Seattle usually sees its first 32°F night about Nov 17, with the first 28°F hard freeze close behind near Dec 2. That first freezing night has ranged from Nov 1 to Dec 6, roughly a 35-day spread. On the spring side, the last 32°F freeze clears around Mar 13 and as late as Apr 1 — the green light for reopening water and de-winterizing. Only about 4 inches of snow falls in a typical year, so cold protection outranks snow removal.

Your frozen pipes checklist

  1. Disconnect, drain, and store garden hoses, then shut off and drain any interior valves that feed outdoor faucets.
  2. Insulate exposed pipes in the garage, crawl space, and along exterior walls with foam sleeves rated for the pipe size.
    Helpful gear: Foam pipe insulation sleeves — Recommended pick
  3. On nights in the low 20s, let a pencil-thin stream of water drip from the faucet farthest from where the line enters.
  4. Open cabinet doors under kitchen and bathroom sinks on outside walls so household heat reaches the plumbing.
  5. Add self-regulating heat cable to the runs most likely to freeze, such as a pipe in an unheated garage.
    Helpful gear: Self-regulating heat cable — Recommended pick
  6. Cap outdoor faucets with insulated covers once the hoses are off.
    Helpful gear: Outdoor faucet covers — Recommended pick
  7. Know where your main shutoff is and confirm it turns; a fast shutoff limits water damage if a line lets go.
  8. If you travel, keep the thermostat at 55°F or higher and ask someone to check the house during a cold snap.
    Helpful gear: Wi-Fi water leak sensor — Recommended pick

What to have on hand

Foam pipe insulation sleeves
Split foam tubing for exposed pipes in crawl spaces and garages.
Recommended pick
Self-regulating heat cable
Thermostatic cable that warms vulnerable runs only when it is cold.
Recommended pick
Outdoor faucet covers
Insulated caps for hose bibs once the hoses come off.
Recommended pick
Wi-Fi water leak sensor
Puck that pings your phone the moment it senses water.
Recommended pick

What this means locally

Compared with nearby cities, Seattle's first-freeze date near Nov 17 sits about a week ahead of Bellevue (Nov 23) and about a week ahead of Kirkland (Nov 23). Washington's deadlines span Sep 23 to Nov 6 statewide — one date for all of Washington would be off by weeks for Seattle. Once you know Seattle's freeze date, use it to shut down your sprinklers and check your car battery too.

Other winter jobs in Seattle

Every task below is dated to Seattle's own freeze and snow normals.

Sprinklers → Nov 22Ice dams → Nov 15Car battery → Dec 2Snow blower → Nov 24Sump pump → Mar 13RV → Nov 22Boat → Nov 25Motorcycle → Nov 17

See the full Seattle winter checklist, in order →

Frequently asked questions

At what temperature do pipes freeze?
Pipes generally come under risk when the temperature outside falls to about 20°F, the threshold many guides use for taking action. Pipes in unheated or exterior-wall spaces freeze sooner than well-insulated interior runs. Wind and poor insulation lower the effective temperature, so a windy night in the mid-20s can be as risky as a still night in the low 20s.
Should I drip my faucets tonight in Seattle?
If the overnight low is forecast at or below about 20°F, letting a thin stream run from the faucet farthest along the line is a low-cost precaution. Moving water is slower to freeze and relieves pressure. Check tonight's low against the live outlook above; freezing nights here typically begin around Nov 17.
How long does it take for pipes to freeze?
There is no fixed clock; it depends on pipe location, insulation, and how far below freezing the air drops. An exposed pipe in a windy, unheated space can freeze in a matter of hours during a hard cold snap, while a protected interior pipe may never reach freezing. The colder and windier it is, the faster it happens.
Which pipes freeze first?
The most exposed pipes freeze first: outdoor hose bibs, and lines in unheated garages, crawl spaces, attics, and along exterior walls. Pipes under sinks on outside walls are common trouble spots. That is why disconnecting hoses and opening cabinet doors on cold nights are two of the highest-value steps.
Does homeowners insurance cover burst pipes?
Sudden, accidental water damage from a frozen pipe is often covered, but insurers may deny a claim if the home was left unheated or the damage is judged to be from neglect. Coverage varies by policy. Keeping the heat on and taking reasonable precautions helps protect both your home and your claim.
What temperature should I keep my house if I'm away?
A common recommendation is to keep the thermostat no lower than 55°F while you are away so interior walls stay warm enough to protect the plumbing. Leaving cabinet doors open and having someone check the house during a cold snap adds a margin of safety, especially for pipes on exterior walls.

Data: NOAA 1991–2020 normals via Seattle Boeing Fld, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.