FrostList

When to Winterize Your Boat in Alpharetta, GA

ON TRACK134 days until first 28°F freezeNov 22

The first 28°F freeze near Alpharetta averages November 22 (1991–2020 normals) — enough to crack an unprotected block even where owners assume they're safe — so winterize the boat by November 15. It's a short step from frost to a hard freeze: roughly 13 days on average.

OUTLOOK

Typical first first 28°F freeze near Nov 22; local deadline about Nov 15. The live 10-day outlook loads here.

Local freeze dates for Alpharetta

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Oct 26Nov 9Nov 27
28°F (hard freeze)Nov 4Nov 22Dec 14
24°F (severe)Nov 15Dec 7Jan 7

NOAA station: Atlanta Peachtree AP · 13.9 mi away · 1,002 ft elevation.

The reference station for Alpharetta is Atlanta Peachtree AP (13.9 mi, 1,002 ft). First freeze there: 32°F by Nov 9, 28°F by Nov 22, 24°F by Dec 7. Year to year the 28°F date has ranged from Nov 4 to Dec 14 — about 40 days apart. Spring's last 32°F freeze clears around Mar 25. Snowfall averages 1 inches a year.

Expect the first frost near Nov 9 in Alpharetta and the first hard freeze by about Nov 22. Year to year, the first 32°F night has fallen anywhere from Oct 26 to Nov 27 — about 32 days apart. Spring's final freeze lands near Mar 25 and as late as Apr 12, so that is when outdoor water and stored gear can safely come back online. Measurable snow is rare, so the freeze near Mar 25 — 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

Alpharetta freezes close to Roswell (Nov 22) and close to Johns Creek (Nov 22) — a reminder that even nearby towns differ by days. Statewide, Georgia prep dates run Nov 12 through Dec 19, which is why Alpharetta gets its own number rather than a Georgia-wide average. The same freeze also decides when to winterize an RV and store a motorcycle.

Other winter jobs in Alpharetta

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

Sprinklers → Nov 12Frozen pipes → Oct 26Car battery → Nov 22Sump pump → Mar 25RV → Nov 12Motorcycle → Nov 9

See the full Alpharetta 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 22 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 GA 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 Atlanta Peachtree AP, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.