FrostList

When to Winterize Your RV in Denver, CO

ON TRACK102 days until first 28°F freezeOct 21

In a typical year, winterize your RV in Denver by October 11. The median first 28°F hard freeze at Denver's NOAA station is October 21 (1991–2020 normals); one year in ten it arrives as early as October 5. Cold deepens quickly here — only about 9 days separate the first frost from that hard freeze.

OUTLOOK

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

Local freeze dates for Denver

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Sep 28Oct 12Oct 26
28°F (hard freeze)Oct 5Oct 21Nov 5
24°F (severe)Oct 14Oct 31Nov 14

NOAA station: Denver Water Dept · 1.2 mi away · 5,228 ft elevation.

Numbers for Denver come from Denver Water Dept, 1.2 miles away at 5,228 feet, where the medians fall 32°F by Oct 12, 28°F by Oct 21, 24°F by Oct 31. Year to year the 28°F date has ranged from Oct 5 to Nov 5 — about 31 days apart. Spring's last 32°F freeze clears around Apr 30. Snowfall averages 41 inches a year, first reaching an inch near October.

Denver usually sees its first 32°F night about Oct 12, with the first 28°F hard freeze close behind near Oct 21. The 32°F date swings from Sep 28 at its earliest to Oct 26 at its latest, near 28 days. The last spring freeze averages Apr 30 and as late as May 13, which sets the safe window for reopening outdoor water and de-winterizing gear. Roughly 41 inches of snow fall in an average year, so a clear roof edge and a running snow blower matter as much as the freeze itself.

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, Denver's first-freeze date near Oct 21 sits later than Lakewood (Oct 16) and close to Commerce City (Oct 18). Colorado's deadlines span Sep 30 to Oct 23 statewide — one date for all of Colorado would be off by weeks for Denver. Once you know Denver's freeze date, use it to shut down your sprinklers and winterize a boat too.

Other winter jobs in Denver

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

Sprinklers → Oct 11Frozen pipes → Sep 28Ice dams → Sep 15Car battery → Oct 21Snow blower → Sep 24Sump pump → Apr 30Boat → Oct 14Motorcycle → Oct 12

See the full Denver 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 Denver?
Wait until the last spring freeze has passed, which averages near Apr 30 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 Denver Water Dept, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.