FrostList

When to Winterize Your RV in Mount Pleasant, SC

ON TRACK158 days until first 28°F freezeDec 16

In a typical year, winterize your RV in Mount Pleasant by December 6. The median first 28°F hard freeze at Mount Pleasant's NOAA station is December 16 (1991–2020 normals); one year in ten it arrives as early as November 25. The early-odds date runs roughly 21 days ahead of the median, so build in that buffer.

OUTLOOK

Typical first first 28°F freeze near Dec 16; local deadline about Dec 6. The live 10-day outlook loads here.

Local freeze dates for Mount Pleasant

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Nov 11Nov 30Dec 24
28°F (hard freeze)Nov 25Dec 16Jan 10
24°F (severe)Dec 5Jan 2Jan 29

NOAA station: Sullivans Is · 5.2 mi away · 5 ft elevation.

For Mount Pleasant, the nearest NOAA station with freeze data is Sullivans Is, 5.2 miles out at 5 feet. Median first-freeze dates there run 32°F by Nov 30, 28°F by Dec 16, 24°F by Jan 2. The 28°F freeze has come as early as Nov 25 and as late as Jan 10, a 46-day spread. Spring's last 32°F freeze clears around Mar 13. Snowfall averages 0 inches a year.

In Mount Pleasant, freezing nights (32°F) typically begin around Nov 30 and the first hard freeze (28°F) follows near Dec 16. The 32°F date swings from Nov 11 at its earliest to Dec 24 at its latest, near 43 days. The last spring freeze averages Mar 13 and as late as Mar 30, which sets the safe window for reopening outdoor water and de-winterizing gear. Snow barely registers here; the freeze date, around Mar 13, is the one that matters.

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

Mount Pleasant freezes later than Charleston (Jan 8) and close to North Charleston (Dec 15) — a reminder that even nearby towns differ by days. Statewide, South Carolina prep dates run Nov 1 through Dec 29, which is why Mount Pleasant gets its own number rather than a South Carolina-wide average. The same freeze also decides when to shut down your sprinklers and winterize a boat.

Other winter jobs in Mount Pleasant

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

Sprinklers → Dec 6Frozen pipes → Nov 11Car battery → Dec 16Sump pump → Mar 13Boat → Dec 9Motorcycle → Nov 30

See the full Mount Pleasant 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 Mount Pleasant?
Wait until the last spring freeze has passed, which averages near Mar 13 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 Sullivans Is, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.