FrostList

When to Winterize Your RV in Frederick, MD

ON TRACK133 days until first 28°F freezeNov 21

Frederick's deadline to winterize your RV is November 11: the local first 28°F freeze runs November 21 on average and November 6 at its earliest (1991–2020 normals). The early-odds date runs roughly 15 days ahead of the median, so build in that buffer.

OUTLOOK

Typical first first 28°F freeze near Nov 21; local deadline about Nov 11. The live 10-day outlook loads here.

Local freeze dates for Frederick

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Oct 23Nov 6Nov 24
28°F (hard freeze)Nov 6Nov 21Dec 11
24°F (severe)Nov 14Dec 7Dec 28

NOAA station: Frederick Police Brks · 1.5 mi away · 380 ft elevation.

For Frederick, the nearest NOAA station with freeze data is Frederick Police Brks, 1.5 miles out at 380 feet. Median first-freeze dates there run 32°F by Nov 6, 28°F by Nov 21, 24°F by Dec 7. The 28°F freeze has come as early as Nov 6 and as late as Dec 11, a 35-day spread. Spring's last 32°F freeze clears around Apr 2. Snowfall averages 31 inches a year, first reaching an inch near December.

In Frederick, freezing nights (32°F) typically begin around Nov 6 and the first hard freeze (28°F) follows near Nov 21. The 32°F date swings from Oct 23 at its earliest to Nov 24 at its latest, near 32 days. The last spring freeze averages Apr 2 and as late as Apr 15, which sets the safe window for reopening outdoor water and de-winterizing gear. About 31 inches of snow a year is enough to justify servicing the snow blower and watching the eaves.

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

Against its neighbors, Frederick (first freeze Nov 21) runs close to Gaithersburg (Nov 19) and later than Leesburg (Nov 5). Across Maryland, local prep deadlines in our data range from Oct 22 to Nov 25, so a statewide rule of thumb would miss Frederick by weeks. In Frederick, that same cold is your cue to shut down your sprinklers and winterize a boat.

Other winter jobs in Frederick

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

Sprinklers → Nov 11Frozen pipes → Oct 23Ice dams → Nov 15Car battery → Nov 21Snow blower → Nov 24Sump pump → Apr 2Boat → Nov 14Motorcycle → Nov 6

See the full Frederick 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 Frederick?
Wait until the last spring freeze has passed, which averages near Apr 2 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 Frederick Police Brks, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.