FrostList

When to Winterize Your Boat in Gresham, OR

ON TRACK157 days until first 28°F freezeDec 15

Plan to haul out and winterize your boat in Gresham by December 8. The first 28°F freeze near Gresham averages December 15 in the 1991–2020 normals, and freeze damage often surprises owners in milder states. The early-to-late range spans roughly 80 days, so treat the median as a midpoint, not a promise.

OUTLOOK

Typical first first 28°F freeze near Dec 15; local deadline about Dec 8. The live 10-day outlook loads here.

Local freeze dates for Gresham

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Oct 30Nov 20Dec 17
28°F (hard freeze)Nov 15Dec 15Feb 3
24°F (severe)Nov 30Jan 1Feb 13

NOAA station: Portland Troutdale AP · 3.7 mi away · 29 ft elevation.

Gresham draws its numbers from Portland Troutdale AP, 29 feet up and 3.7 miles away. Its median first-freeze dates are 32°F by Nov 20, 28°F by Dec 15, 24°F by Jan 1. That hard freeze has landed anywhere from Nov 15 to Feb 3, a swing of roughly 80 days. Spring's last 32°F freeze clears around Mar 16. Snowfall averages 3 inches a year, first reaching an inch near December.

Gresham usually sees its first 32°F night about Nov 20, with the first 28°F hard freeze close behind near Dec 15. The 32°F date swings from Oct 30 at its earliest to Dec 17 at its latest, near 48 days. The last spring freeze averages Mar 16 and as late as Apr 12, which sets the safe window for reopening outdoor water and de-winterizing gear. At about 3 inches of snow a year, the freeze — not snow load — is the thing to plan around.

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

Gresham freezes about a week ahead of Portland (Dec 20) and later than Lake Oswego (Dec 8) — a reminder that even nearby towns differ by days. Statewide, Oregon prep dates run Sep 27 through Dec 14, which is why Gresham gets its own number rather than a Oregon-wide average. The same freeze also decides when to winterize an RV and store a motorcycle.

Other winter jobs in Gresham

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

Sprinklers → Dec 5Frozen pipes → Oct 30Ice dams → Nov 15Car battery → Dec 15Snow blower → Nov 24Sump pump → Mar 16RV → Dec 5Motorcycle → Nov 20

See the full Gresham 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 15 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 Portland Troutdale AP, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.