FrostList

When to Winterize Your RV in Nampa, ID

ON TRACK106 days until first 28°F freezeOct 25

Aim to winterize your RV in Nampa by October 15, roughly a week and a half before the median first 28°F freeze of October 25, which one fall in ten shows up by October 9. Cold deepens quickly here — only about 12 days separate the first frost from that hard freeze.

OUTLOOK

Typical first first 28°F freeze near Oct 25; local deadline about Oct 15. The live 10-day outlook loads here.

Local freeze dates for Nampa

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Sep 29Oct 13Oct 28
28°F (hard freeze)Oct 9Oct 25Nov 10
24°F (severe)Oct 22Nov 6Nov 24

NOAA station: Nampa Sugar Factory · 4.4 mi away · 2,470 ft elevation.

Numbers for Nampa come from Nampa Sugar Factory, 4.4 miles away at 2,470 feet, where the medians fall 32°F by Oct 13, 28°F by Oct 25, 24°F by Nov 6. Year to year the 28°F date has ranged from Oct 9 to Nov 10 — about 32 days apart. Spring's last 32°F freeze clears around Apr 29. Snowfall averages 10 inches a year, first reaching an inch near December.

In Nampa, freezing nights (32°F) typically begin around Oct 13 and the first hard freeze (28°F) follows near Oct 25. That first freezing night has ranged from Sep 29 to Oct 28, roughly a 29-day spread. On the spring side, the last 32°F freeze clears around Apr 29 and as late as May 18 — the green light for reopening water and de-winterizing. Only about 10 inches of snow falls in a typical year, so cold protection outranks snow removal.

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, Nampa's first-freeze date near Oct 25 sits about a week ahead of Meridian (Oct 31) and about a week ahead of Caldwell (Oct 30). Idaho's deadlines span Oct 3 to Oct 22 statewide — one date for all of Idaho would be off by weeks for Nampa. Once you know Nampa's freeze date, use it to shut down your sprinklers and winterize a boat too.

Other winter jobs in Nampa

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

Sprinklers → Oct 15Frozen pipes → Sep 29Ice dams → Nov 15Car battery → Oct 25Snow blower → Nov 24Sump pump → Apr 29Boat → Oct 18Motorcycle → Oct 13

See the full Nampa 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 Nampa?
Wait until the last spring freeze has passed, which averages near Apr 29 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 Nampa Sugar Factory, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.