FrostList

When to Winterize Your Boat in Beaverton, OR

ON TRACK163 days until first 28°F freezeDec 21

In Beaverton, target December 14 to drain, antifreeze, and lay up the boat, about a week before the median first 28°F freeze of December 21; a surprise cold snap is exactly how freeze claims happen. Year to year the date swings about 73 days, which is why the live outlook beats the calendar.

OUTLOOK

Typical first first 28°F freeze near Dec 21; local deadline about Dec 14. The live 10-day outlook loads here.

Local freeze dates for Beaverton

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Nov 11Dec 5Jan 12
28°F (hard freeze)Nov 24Dec 21Feb 5
24°F (severe)Dec 2Dec 30Feb 5

NOAA station: Nature Park-Beaverton · 1.9 mi away · 185 ft elevation.

Numbers for Beaverton come from Nature Park-Beaverton, 1.9 miles away at 185 feet, where the medians fall 32°F by Dec 5, 28°F by Dec 21, 24°F by Dec 30. Year to year the 28°F date has ranged from Nov 24 to Feb 5 — about 73 days apart. Spring's last 32°F freeze clears around Feb 11. Snowfall averages 4 inches a year, first reaching an inch near January.

In Beaverton, freezing nights (32°F) typically begin around Dec 5 and the first hard freeze (28°F) follows near Dec 21. Year to year, the first 32°F night has fallen anywhere from Nov 11 to Jan 12 — about 62 days apart. Spring's final freeze lands near Feb 11 and as late as Mar 5, so that is when outdoor water and stored gear can safely come back online. Snow is light here, near 4 inches a year, so pipe and battery cold usually matters more than plowing.

Your boat checklist

  1. Change the engine oil and filter while the motor is warm so contaminants leave with the old oil.
  2. Run the engine on antifreeze until pink fluid reaches the outlet, protecting the block and manifolds.
    Helpful gear: Marine antifreeze — Recommended pick
  3. Fog the cylinders with fogging oil as the engine runs down to coat internal parts against corrosion.
    Helpful gear: Fogging oil — Recommended pick
  4. Top off the fuel tank and add stabilizer to limit condensation and protect ethanol-blend fuel.
    Helpful gear: Marine fuel stabilizer — Recommended pick
  5. Drain the raw-water system, the livewell, and any washdown lines that can trap water.
  6. Remove the battery, charge it fully, and keep it on a maintainer over the layup.
    Helpful gear: Battery maintainer — Recommended pick
  7. Support the cover so snow and rain shed off, and leave vents so the interior can breathe.
  8. For an inboard or sterndrive, follow the manual closely — those blocks are the ones freeze claims hit hardest.

What to have on hand

Marine antifreeze
Propylene-glycol fluid rated for engine blocks and systems.
Recommended pick
Marine fuel stabilizer
Additive that protects ethanol-blend fuel over the layup.
Recommended pick
Fogging oil
Spray that coats cylinders against corrosion in storage.
Recommended pick
Battery maintainer
Keeps the cranking battery topped off on the trailer.
Recommended pick

What this means locally

Against its neighbors, Beaverton (first freeze Dec 21) runs later than Tigard (Nov 30) and close to Portland (Dec 20). Across Oregon, local prep deadlines in our data range from Sep 27 to Dec 14, so a statewide rule of thumb would miss Beaverton by weeks. In Beaverton, that same cold is your cue to winterize an RV and store a motorcycle.

Other winter jobs in Beaverton

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

Sprinklers → Dec 11Frozen pipes → Nov 11Ice dams → Dec 16Car battery → Dec 21Snow blower → Dec 25Sump pump → Feb 11RV → Dec 11Motorcycle → Dec 5

See the full Beaverton winter checklist, in order →

Frequently asked questions

At what temperature does a boat engine block crack?
Trapped water in an engine block or manifold can freeze and crack the casting once temperatures fall below 32°F and stay there long enough. Inboard and sterndrive blocks hold the most water and are the most vulnerable. Draining fully and adding antifreeze before the first hard freeze near Dec 21 is the protection.
Do outboards need winterizing?
Yes. An outboard should be drained so no water sits in the powerhead or lower unit, and the fuel system stabilized. Outboards self-drain better than inboards when tilted down, but fogging the cylinders and changing the gear oil are still part of a proper layup.
Fogging oil: is it necessary?
Fogging coats the cylinder walls and internal parts with a film that resists corrosion during months of storage. On engines that sit all winter it is cheap insurance against rust, especially in humid or coastal storage. Follow your engine maker's guidance on how to apply it.
How much does boat winterization cost?
A professional winterization varies with engine type and boat size, and inboards cost more than a simple outboard. Doing it yourself costs mainly antifreeze, oil, and fogging oil. Either way, the bill is far smaller than repairing a cracked block, which is the failure winterizing prevents.
Do boats in OR really need winterizing?
If temperatures reach freezing where the boat is stored, yes. Freeze claims are common in milder states precisely because owners assume they are safe and skip the step, then a rare cold snap cracks a block. Check the local freeze dates above and protect the engine before the first hard freeze.
When should I de-winterize my boat?
De-winterize in spring once the risk of a hard freeze has passed for your area. Reconnect and charge the battery, replace drain plugs, check hoses and clamps, and inspect the fuel system before the first launch. Reopening too early leaves the block exposed to a late cold snap.

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