FrostList

When to Winterize Your RV in Porterville, CA

ON TRACK165 days until first 28°F freezeDec 23

Aim to winterize your RV in Porterville by December 13, roughly a week and a half before the median first 28°F freeze of December 23, which one fall in ten shows up by December 4. The early-odds date runs roughly 19 days ahead of the median, so build in that buffer.

OUTLOOK

Typical first first 28°F freeze near Dec 23; local deadline about Dec 13. The live 10-day outlook loads here.

Local freeze dates for Porterville

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Nov 26Dec 13Jan 6
28°F (hard freeze)Dec 4Dec 23Jan 13
24°F (severe)Dec 8Dec 24Jan 8

NOAA station: Porterville · 0.3 mi away · 393 ft elevation.

Numbers for Porterville come from Porterville, 0.3 miles away at 393 feet, where the medians fall 32°F by Dec 13, 28°F by Dec 23, 24°F by Dec 24. The 28°F freeze has come as early as Dec 4 and as late as Jan 13, a 40-day spread. Spring's last 32°F freeze clears around Jan 20. Snowfall averages 0 inches a year.

In Porterville, freezing nights (32°F) typically begin around Dec 13 and the first hard freeze (28°F) follows near Dec 23. The 32°F date swings from Nov 26 at its earliest to Jan 6 at its latest, near 41 days. The last spring freeze averages Jan 20 and as late as Feb 22, which sets the safe window for reopening outdoor water and de-winterizing gear. Snow barely registers here; the freeze date, around Jan 20, 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, Porterville's first-freeze date near Dec 23 sits close to Tulare (Dec 25) and close to Visalia (Dec 25). California's deadlines span Jan 6 to Dec 27 statewide — one date for all of California would be off by weeks for Porterville. Once you know Porterville's freeze date, use it to shut down your sprinklers and winterize a boat too.

Other winter jobs in Porterville

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

Sprinklers → Dec 13Frozen pipes → Nov 26Car battery → Dec 23Sump pump → Jan 20Boat → Dec 16Motorcycle → Dec 13

See the full Porterville 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 Porterville?
Wait until the last spring freeze has passed, which averages near Jan 20 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 Porterville, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.