FrostList

When to Winterize Your Boat in Cheyenne, WY

ON TRACK91 days until first 28°F freezeOct 10

Plan to haul out and winterize your boat in Cheyenne by October 3. The first 28°F freeze near Cheyenne averages October 10 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 Oct 10; local deadline about Oct 3. The live 10-day outlook loads here.

Local freeze dates for Cheyenne

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Sep 17Oct 1Oct 14
28°F (hard freeze)Sep 27Oct 10Oct 23
24°F (severe)Oct 4Oct 19Nov 3

NOAA station: Cheyenne WFO · 1.1 mi away · 6,119 ft elevation.

For Cheyenne, the nearest NOAA station with freeze data is Cheyenne WFO, 1.1 miles out at 6,119 feet. Median first-freeze dates there run 32°F by Oct 1, 28°F by Oct 10, 24°F by Oct 19. Year to year the 28°F date has ranged from Sep 27 to Oct 23 — about 26 days apart. Spring's last 32°F freeze clears around May 14. Snowfall averages 66 inches a year, first reaching an inch near October.

Cheyenne usually sees its first 32°F night about Oct 1, with the first 28°F hard freeze close behind near Oct 10. The 32°F date swings from Sep 17 at its earliest to Oct 14 at its latest, near 27 days. The last spring freeze averages May 14 and as late as May 28, which sets the safe window for reopening outdoor water and de-winterizing gear. Roughly 66 inches of snow fall in an average year, so a clear roof edge and a running snow blower matter as much as the freeze itself.

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

Cheyenne freezes about a week ahead of Fort Collins (Oct 17) and about a week ahead of Greeley (Oct 18) — a reminder that even nearby towns differ by days. Statewide, Wyoming prep dates run Sep 29 through Oct 3, which is why Cheyenne gets its own number rather than a Wyoming-wide average. The same freeze also decides when to winterize an RV and store a motorcycle.

Other winter jobs in Cheyenne

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

Sprinklers → Sep 30Frozen pipes → Sep 17Ice dams → Sep 15Car battery → Oct 10Snow blower → Sep 24Sump pump → May 14RV → Sep 30Motorcycle → Oct 1

See the full Cheyenne 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 10 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 WY 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 Cheyenne WFO, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.