FrostList

When to Winterize Your RV in Portland, OR

ON TRACK162 days until first 28°F freezeDec 20

Aim to winterize your RV in Portland by December 10, roughly a week and a half before the median first 28°F freeze of December 20, which one fall in ten shows up by November 25. It's a short step from frost to a hard freeze: roughly 19 days on average.

OUTLOOK

Typical first first 28°F freeze near Dec 20; local deadline about Dec 10. The live 10-day outlook loads here.

Local freeze dates for Portland

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Nov 10Dec 1Dec 27
28°F (hard freeze)Nov 25Dec 20Jan 30
24°F (severe)Nov 30Dec 29Feb 11

NOAA station: Portland Kgw-Tv · 0.7 mi away · 159 ft elevation.

Numbers for Portland come from Portland Kgw-Tv, 0.7 miles away at 159 feet, where the medians fall 32°F by Dec 1, 28°F by Dec 20, 24°F by Dec 29. The 28°F freeze has come as early as Nov 25 and as late as Jan 30, a 66-day spread. Spring's last 32°F freeze clears around Feb 25. Snowfall averages 4 inches a year, first reaching an inch near January.

Expect the first frost near Dec 1 in Portland and the first hard freeze by about Dec 20. Year to year, the first 32°F night has fallen anywhere from Nov 10 to Dec 27 — about 47 days apart. Spring's final freeze lands near Feb 25 and as late as Mar 21, so that is when outdoor water and stored gear can safely come back online. Snow is light here, near 4 inches a year, so pipe and battery cold usually matters more than plowing.

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, Portland (first freeze Dec 20) runs close to Beaverton (Dec 21) and later than Lake Oswego (Dec 8). Across Oregon, local prep deadlines in our data range from Sep 24 to Dec 11, so a statewide rule of thumb would miss Portland by weeks. In Portland, that same cold is your cue to shut down your sprinklers and winterize a boat.

Other winter jobs in Portland

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

Sprinklers → Dec 10Frozen pipes → Nov 10Ice dams → Dec 16Car battery → Dec 20Snow blower → Dec 25Sump pump → Feb 25Boat → Dec 13Motorcycle → Dec 1

See the full Portland 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 Portland?
Wait until the last spring freeze has passed, which averages near Feb 25 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 Portland Kgw-Tv, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.