FrostList

When to Winterize Your Boat in Lompoc, CA

ON TRACK171 days until first 28°F freezeDec 29

The first 28°F freeze near Lompoc averages December 29 (1991–2020 normals) — enough to crack an unprotected block even where owners assume they're safe — so winterize the boat by December 22. Year to year the date swings about 51 days, which is why the live outlook beats the calendar.

OUTLOOK

Typical first first 28°F freeze near Dec 29; local deadline about Dec 22. The live 10-day outlook loads here.

Local freeze dates for Lompoc

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Nov 27Dec 19Jan 26
28°F (hard freeze)Dec 9Dec 29Jan 29

NOAA station: Lompoc · 1.1 mi away · 75 ft elevation.

For Lompoc, the nearest NOAA station with freeze data is Lompoc, 1.1 miles out at 75 feet. Median first-freeze dates there run 32°F by Dec 19, 28°F by Dec 29. Year to year the 28°F date has ranged from Dec 9 to Jan 29 — about 51 days apart. Spring's last 32°F freeze clears around Jan 20.

The freeze arrives in two steps in Lompoc: 32°F around Dec 19, then a hard 28°F near Dec 29. Year to year, the first 32°F night has fallen anywhere from Nov 27 to Jan 26 — about 60 days apart. Spring's final freeze lands near Jan 20 and as late as Feb 24, so that is when outdoor water and stored gear can safely come back online. Measurable snow is rare, so the freeze near Jan 20 — 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

Compared with nearby cities, Lompoc's first-freeze date near Dec 29 sits close to Santa Maria (Dec 27) and later than San Luis Obispo (Jan 6). California's deadlines span Jan 9 to Dec 30 statewide — one date for all of California would be off by weeks for Lompoc. Once you know Lompoc's freeze date, use it to winterize an RV and store a motorcycle too.

Other winter jobs in Lompoc

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

Sprinklers → Dec 19Frozen pipes → Nov 27Car battery → Dec 29Sump pump → Jan 20RV → Dec 19Motorcycle → Dec 19

See the full Lompoc 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 29 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 CA 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 Lompoc, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.