FrostList

When to Winterize Your Boat in Kennewick, WA

ON TRACK123 days until first 28°F freezeNov 11

Plan to haul out and winterize your boat in Kennewick by November 4. The first 28°F freeze near Kennewick averages November 11 in the 1991–2020 normals, and freeze damage often surprises owners in milder states. Year to year the date swings about 35 days, which is why the live outlook beats the calendar.

OUTLOOK

Typical first first 28°F freeze near Nov 11; local deadline about Nov 4. The live 10-day outlook loads here.

Local freeze dates for Kennewick

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Oct 18Oct 30Nov 15
28°F (hard freeze)Oct 27Nov 11Dec 1
24°F (severe)Nov 5Nov 25Dec 20

NOAA station: Kennewick · 1.7 mi away · 390 ft elevation.

Numbers for Kennewick come from Kennewick, 1.7 miles away at 390 feet, where the medians fall 32°F by Oct 30, 28°F by Nov 11, 24°F by Nov 25. The 28°F freeze has come as early as Oct 27 and as late as Dec 1, a 35-day spread. Spring's last 32°F freeze clears around Mar 28. Snowfall averages 2 inches a year, first reaching an inch near December.

The freeze arrives in two steps in Kennewick: 32°F around Oct 30, then a hard 28°F near Nov 11. Year to year, the first 32°F night has fallen anywhere from Oct 18 to Nov 15 — about 28 days apart. Spring's final freeze lands near Mar 28 and as late as Apr 10, so that is when outdoor water and stored gear can safely come back online. Measurable snow is rare, so the freeze near Mar 28 — not snow load — drives the local prep list.

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, Kennewick (first freeze Nov 11) runs close to Pasco (Nov 11) and later than Richland (Nov 4). Across Washington, local prep deadlines in our data range from Oct 9 to Dec 4, so a statewide rule of thumb would miss Kennewick by weeks. In Kennewick, that same cold is your cue to winterize an RV and store a motorcycle.

Other winter jobs in Kennewick

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

Sprinklers → Nov 1Frozen pipes → Oct 18Car battery → Nov 11Sump pump → Mar 28RV → Nov 1Motorcycle → Oct 30

See the full Kennewick 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 Nov 11 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 WA 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 Kennewick, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.