FrostList

When to Winterize Your RV in San Rafael, CA

ON TRACK166 days until first 28°F freezeDec 24

San Rafael's deadline to winterize your RV is December 14: the local first 28°F freeze runs December 24 on average and December 4 at its earliest (1991–2020 normals). The early-odds date runs roughly 20 days ahead of the median, so build in that buffer.

OUTLOOK

Typical first first 28°F freeze near Dec 24; local deadline about Dec 14. The live 10-day outlook loads here.

Local freeze dates for San Rafael

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Nov 30Dec 18Jan 19
28°F (hard freeze)Dec 4Dec 24Jan 21

NOAA station: Kentfield · 1.4 mi away · 145 ft elevation.

Numbers for San Rafael come from Kentfield, 1.4 miles away at 145 feet, where the medians fall 32°F by Dec 18, 28°F by Dec 24. The 28°F freeze has come as early as Dec 4 and as late as Jan 21, a 48-day spread. Spring's last 32°F freeze clears around Jan 16.

In San Rafael, freezing nights (32°F) typically begin around Dec 18 and the first hard freeze (28°F) follows near Dec 24. The 32°F date swings from Nov 30 at its earliest to Jan 19 at its latest, near 50 days. The last spring freeze averages Jan 16 and as late as Feb 25, which sets the safe window for reopening outdoor water and de-winterizing gear. Snow barely registers here; the freeze date, around Jan 16, 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

Compared with nearby cities, San Rafael's first-freeze date near Dec 24 sits about a week ahead of Novato (Dec 29) and later than Vallejo (Jan 2). California's deadlines span Jan 6 to Dec 27 statewide — one date for all of California would be off by weeks for San Rafael. Once you know San Rafael's freeze date, use it to shut down your sprinklers and winterize a boat too.

Other winter jobs in San Rafael

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

Sprinklers → Dec 14Frozen pipes → Nov 30Car battery → Dec 24Sump pump → Jan 16Boat → Dec 17Motorcycle → Dec 18

See the full San Rafael 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 San Rafael?
Wait until the last spring freeze has passed, which averages near Jan 16 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 Kentfield, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.