FrostList

When to Winterize Your RV in Charleston, SC

SEASON PASSED181 days until first 28°F freezeJan 8

Charleston's deadline to winterize your RV is December 29: the local first 28°F freeze runs January 8 on average and December 15 at its earliest (1991–2020 normals). It's a short step from frost to a hard freeze: roughly 9 days on average.

OUTLOOK

Typical first first 28°F freeze near Jan 8; local deadline about Dec 29. The live 10-day outlook loads here.

Local freeze dates for Charleston

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Dec 2Dec 30Jan 25
28°F (hard freeze)Dec 15Jan 8Feb 3
24°F (severe)Dec 22Jan 15Feb 2

NOAA station: Charleston City · 0.2 mi away · 10 ft elevation.

The reference station for Charleston is Charleston City (0.2 mi, 10 ft). First freeze there: 32°F by Dec 30, 28°F by Jan 8, 24°F by Jan 15. That hard freeze has landed anywhere from Dec 15 to Feb 3, a swing of roughly 50 days. Spring's last 32°F freeze clears around Feb 4. Snowfall averages 0 inches a year.

Expect the first frost near Dec 30 in Charleston and the first hard freeze by about Jan 8. Year to year, the first 32°F night has fallen anywhere from Dec 2 to Jan 25 — about 54 days apart. Spring's final freeze lands near Feb 4 and as late as Mar 4, so that is when outdoor water and stored gear can safely come back online. Measurable snow is rare, so the freeze near Feb 4 — not snow load — drives the local prep list.

Your rv checklist

  1. Drain the fresh, gray, and black tanks, then drain the water heater only after it has cooled and lost pressure.
  2. Bypass the water heater so you do not waste six gallons of antifreeze filling the tank.
  3. Blow out the lines with a compressor at about 30–40 psi, then pump non-toxic RV antifreeze through every faucet until it runs pink.
    Helpful gear: RV antifreeze (6-pack) — Recommended pick
  4. Use a water-pump converter kit to draw antifreeze straight from the jug through the plumbing.
    Helpful gear: Water pump converter kit — Recommended pick
  5. Pour a cup of antifreeze into each drain trap and the toilet to protect the seals.
  6. Fit a blow-out plug at the city-water inlet so you can clear that line too.
    Helpful gear: Blow-out plug — Recommended pick
  7. Remove batteries or put them on a maintainer, and store them off a cold concrete floor.
  8. Cover roof vents, close the propane, and set out traps or deterrents so mice do not move in.

What to have on hand

RV antifreeze (6-pack)
Non-toxic pink fluid for the fresh-water plumbing and traps.
Recommended pick
Water pump converter kit
Siphon kit that draws antifreeze straight through the pump.
Recommended pick
Blow-out plug
Adapter that lets a compressor clear the lines before antifreeze.
Recommended pick
Heated fresh-water hose
For anyone staying hooked up through a cold snap.
Recommended pick

What this means locally

Compared with nearby cities, Charleston's first-freeze date near Jan 8 sits about a week ahead of North Charleston (Dec 15) and about a week ahead of Mount Pleasant (Dec 16). South Carolina's deadlines span Nov 1 to Dec 29 statewide — one date for all of South Carolina would be off by weeks for Charleston. Once you know Charleston's freeze date, use it to shut down your sprinklers and winterize a boat too.

Other winter jobs in Charleston

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

Sprinklers → Dec 29Frozen pipes → Dec 2Car battery → Jan 8Sump pump → Feb 4Boat → Jan 1Motorcycle → Dec 30

See the full Charleston winter checklist, in order →

Frequently asked questions

At what temperature do RV pipes freeze?
An RV's exposed plumbing and thin-walled tanks can begin to freeze once temperatures sit in the mid-20s for a few hours, sooner than a house because there is little insulation around the lines. That is why the winterizing deadline tracks the first 28°F freeze rather than the first light frost.
How much RV antifreeze do I need?
Most travel trailers and motorhomes take about two to three gallons of non-toxic RV antifreeze, and larger rigs more. Bypassing the water heater saves roughly six gallons you would otherwise waste filling the tank. Buy an extra jug; stores sell out once the first freeze warnings hit.
Can I just use my RV furnace instead of winterizing?
Relying on the furnace is risky. A propane run-out, a tripped breaker, or a dead battery during a cold night leaves the plumbing unprotected, and the furnace may not keep the underbelly and bays warm enough anyway. Draining and adding antifreeze is the dependable way to protect the system.
How do I winterize an RV water heater?
Let the tank cool and lose pressure, then drain it and, if fitted, pull the anode rod. Do not add antifreeze to the water heater tank; instead, set the bypass valves so antifreeze skips the tank and fills only the lines. Fresh antifreeze in an unbypassed heater just wastes several gallons.
When is it safe to de-winterize an RV in Charleston?
Wait until the last spring freeze has passed, which averages near Feb 4 here. De-winterize by flushing the antifreeze from the lines, sanitizing the fresh tank, and checking for leaks before a trip. Reopening too early risks a surprise late freeze on a charged system.
Do I need to winterize an RV stored indoors?
A reliably heated indoor space that stays above freezing protects the plumbing, so full winterizing may not be needed. But an unheated garage or barn can still drop below freezing on a cold night. If you cannot guarantee the space stays warm, winterize to be safe.

Data: NOAA 1991–2020 normals via Charleston City, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.