FrostList

When to Winterize Your Boat in Flower Mound, TX

ON TRACK141 days until first 28°F freezeNov 29

Freeze protection for a Flower Mound boat keys off the first 28°F freeze, which averages November 29, so haul out and winterize by November 22 to beat it. Cold deepens quickly here — only about 12 days separate the first frost from that hard freeze.

OUTLOOK

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

Local freeze dates for Flower Mound

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Nov 2Nov 17Dec 4
28°F (hard freeze)Nov 9Nov 29Dec 20
24°F (severe)Nov 18Dec 13Jan 14

NOAA station: Grapevine Dam · 5.0 mi away · 585 ft elevation.

For Flower Mound, the nearest NOAA station with freeze data is Grapevine Dam, 5.0 miles out at 585 feet. Median first-freeze dates there run 32°F by Nov 17, 28°F by Nov 29, 24°F by Dec 13. The 28°F freeze has come as early as Nov 9 and as late as Dec 20, a 41-day spread. Spring's last 32°F freeze clears around Mar 14. Snowfall averages 0 inches a year.

In Flower Mound, freezing nights (32°F) typically begin around Nov 17 and the first hard freeze (28°F) follows near Nov 29. That first freezing night has ranged from Nov 2 to Dec 4, roughly a 32-day spread. On the spring side, the last 32°F freeze clears around Mar 14 and as late as Apr 3 — the green light for reopening water and de-winterizing. With almost no snow in a normal year, cold — not plowing — sets the calendar, and it centers on Mar 14.

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, Flower Mound (first freeze Nov 29) runs close to Grapevine (Nov 29) and close to Coppell (Nov 29). Across Texas, local prep deadlines in our data range from Jan 1 to Dec 29, so a statewide rule of thumb would miss Flower Mound by weeks. In Flower Mound, that same cold is your cue to winterize an RV and store a motorcycle.

Other winter jobs in Flower Mound

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

Sprinklers → Nov 19Frozen pipes → Nov 2Car battery → Nov 29Sump pump → Mar 14RV → Nov 19Motorcycle → Nov 17

See the full Flower Mound 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 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 TX 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 Grapevine Dam, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.