FrostList

When to Winterize Your RV in Sioux City, IA

ON TRACK99 days until first 28°F freezeOct 18

Sioux City's deadline to winterize your RV is October 8: the local first 28°F freeze runs October 18 on average and October 2 at its earliest (1991–2020 normals). Year to year the date swings about 28 days, which is why the live outlook beats the calendar.

OUTLOOK

Typical first first 28°F freeze near Oct 18; local deadline about Oct 8. The live 10-day outlook loads here.

Local freeze dates for Sioux City

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Sep 24Oct 7Oct 21
28°F (hard freeze)Oct 2Oct 18Oct 30
24°F (severe)Oct 14Oct 27Nov 9

NOAA station: Sioux City Ang · 7.2 mi away · 1,100 ft elevation.

The reference station for Sioux City is Sioux City Ang (7.2 mi, 1,100 ft). First freeze there: 32°F by Oct 7, 28°F by Oct 18, 24°F by Oct 27. Year to year the 28°F date has ranged from Oct 2 to Oct 30 — about 28 days apart. Spring's last 32°F freeze clears around Apr 29. Snowfall averages 36 inches a year, first reaching an inch near November.

The freeze arrives in two steps in Sioux City: 32°F around Oct 7, then a hard 28°F near Oct 18. Year to year, the first 32°F night has fallen anywhere from Sep 24 to Oct 21 — about 27 days apart. Spring's final freeze lands near Apr 29 and as late as May 11, so that is when outdoor water and stored gear can safely come back online. Snowfall averages roughly 36 inches a year — enough that a working snow blower and a clear roof edge earn their keep.

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, Sioux City's first-freeze date near Oct 18 sits about a week ahead of Sioux Falls (Oct 24) and about a week ahead of Omaha (Oct 30). Iowa's deadlines span Oct 8 to Oct 22 statewide — one date for all of Iowa would be off by weeks for Sioux City. Once you know Sioux City's freeze date, use it to shut down your sprinklers and winterize a boat too.

Other winter jobs in Sioux City

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

Sprinklers → Oct 8Frozen pipes → Sep 24Ice dams → Oct 16Car battery → Oct 18Snow blower → Oct 25Sump pump → Apr 29Boat → Oct 11Motorcycle → Oct 7

See the full Sioux City 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 Sioux City?
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 Sioux City Ang, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.