FrostList

When to Winterize Your Boat in Yakima, WA

ON TRACK97 days until first 28°F freezeOct 16

Freeze protection for a Yakima boat keys off the first 28°F freeze, which averages October 16, so haul out and winterize by October 9 to beat it. The early-odds date runs roughly 14 days ahead of the median, so build in that buffer.

OUTLOOK

Typical first first 28°F freeze near Oct 16; local deadline about Oct 9. The live 10-day outlook loads here.

Local freeze dates for Yakima

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Sep 23Oct 4Oct 17
28°F (hard freeze)Oct 2Oct 16Nov 1
24°F (severe)Oct 13Oct 28Nov 12

NOAA station: Yakima Air Terminal · 2.9 mi away · 1,064 ft elevation.

For Yakima, the nearest NOAA station with freeze data is Yakima Air Terminal, 2.9 miles out at 1,064 feet. Median first-freeze dates there run 32°F by Oct 4, 28°F by Oct 16, 24°F by Oct 28. The 28°F freeze has come as early as Oct 2 and as late as Nov 1, a 30-day spread. Spring's last 32°F freeze clears around May 8. Snowfall averages 20 inches a year, first reaching an inch near November.

In Yakima, freezing nights (32°F) typically begin around Oct 4 and the first hard freeze (28°F) follows near Oct 16. The 32°F date swings from Sep 23 at its earliest to Oct 17 at its latest, near 24 days. The last spring freeze averages May 8 and as late as May 27, which sets the safe window for reopening outdoor water and de-winterizing gear. About 20 inches of snow a year is enough to justify servicing the snow blower and watching the eaves.

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

Yakima freezes about a week ahead of Richland (Nov 4) and about a week ahead of Kennewick (Nov 11) — a reminder that even nearby towns differ by days. Statewide, Washington prep dates run Oct 9 through Dec 4, which is why Yakima gets its own number rather than a Washington-wide average. The same freeze also decides when to winterize an RV and store a motorcycle.

Other winter jobs in Yakima

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

Sprinklers → Oct 6Frozen pipes → Sep 23Ice dams → Oct 16Car battery → Oct 16Snow blower → Oct 25Sump pump → May 8RV → Oct 6Motorcycle → Oct 4

See the full Yakima 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 Oct 16 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 Yakima Air Terminal, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.