FrostList

When to Winterize Your Boat in Des Plaines, IL

ON TRACK119 days until first 28°F freezeNov 7

Plan to haul out and winterize your boat in Des Plaines by October 31. The first 28°F freeze near Des Plaines averages November 7 in the 1991–2020 normals, and freeze damage often surprises owners in milder states. The early-to-late range spans roughly 26 days, so treat the median as a midpoint, not a promise.

OUTLOOK

Typical first first 28°F freeze near Nov 7; local deadline about Oct 31. The live 10-day outlook loads here.

Local freeze dates for Des Plaines

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Oct 15Oct 28Nov 11
28°F (hard freeze)Oct 27Nov 7Nov 22
24°F (severe)Nov 3Nov 17Dec 2

NOAA station: Chicago Ohare Intl AP · 3.7 mi away · 658 ft elevation.

The reference station for Des Plaines is Chicago Ohare Intl AP (3.7 mi, 658 ft). First freeze there: 32°F by Oct 28, 28°F by Nov 7, 24°F by Nov 17. That hard freeze has landed anywhere from Oct 27 to Nov 22, a swing of roughly 26 days. Spring's last 32°F freeze clears around Apr 16. Snowfall averages 38 inches a year, first reaching an inch near November.

Des Plaines usually sees its first 32°F night about Oct 28, with the first 28°F hard freeze close behind near Nov 7. The 32°F date swings from Oct 15 at its earliest to Nov 11 at its latest, near 27 days. The last spring freeze averages Apr 16 and as late as May 1, which sets the safe window for reopening outdoor water and de-winterizing gear. About 38 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

Against its neighbors, Des Plaines (first freeze Nov 7) runs close to Park Ridge (Nov 7) and close to Mount Prospect (Nov 7). Across Illinois, local prep deadlines in our data range from Oct 17 to Nov 8, so a statewide rule of thumb would miss Des Plaines by weeks. In Des Plaines, that same cold is your cue to winterize an RV and store a motorcycle.

Other winter jobs in Des Plaines

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

Sprinklers → Oct 28Frozen pipes → Oct 15Ice dams → Oct 16Car battery → Nov 7Snow blower → Oct 25Sump pump → Apr 16RV → Oct 28Motorcycle → Oct 28

See the full Des Plaines 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 7 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 IL 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 Chicago Ohare Intl AP, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.