FrostList

When to Winterize Your RV in Bismarck, ND

ON TRACK90 days until first 28°F freezeOct 9

In a typical year, winterize your RV in Bismarck by September 29. The median first 28°F hard freeze at Bismarck's NOAA station is October 9 (1991–2020 normals); one year in ten it arrives as early as September 25. It's a short step from frost to a hard freeze: roughly 9 days on average.

OUTLOOK

Typical first first 28°F freeze near Oct 9; local deadline about Sep 29. The live 10-day outlook loads here.

Local freeze dates for Bismarck

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Sep 16Sep 30Oct 13
28°F (hard freeze)Sep 25Oct 9Oct 22
24°F (severe)Oct 2Oct 18Nov 1

NOAA station: Bismarck 2.4 Nnw · 1.9 mi away · 1,831 ft elevation.

Bismarck draws its numbers from Bismarck 2.4 Nnw, 1,831 feet up and 1.9 miles away. Its median first-freeze dates are 32°F by Sep 30, 28°F by Oct 9, 24°F by Oct 18. That hard freeze has landed anywhere from Sep 25 to Oct 22, a swing of roughly 27 days. Spring's last 32°F freeze clears around May 10. Snowfall averages 50 inches a year, first reaching an inch near October.

Bismarck usually sees its first 32°F night about Sep 30, with the first 28°F hard freeze close behind near Oct 9. Year to year, the first 32°F night has fallen anywhere from Sep 16 to Oct 13 — about 27 days apart. Spring's final freeze lands near May 10 and as late as May 23, so that is when outdoor water and stored gear can safely come back online. With about 50 inches of snow a year, roof, snow-blower, and ice-dam prep all belong on the same calendar.

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, Bismarck's first-freeze date near Oct 9 sits close to Minot (Oct 10) and close to Pierre (Oct 12). North Dakota's deadlines span Sep 29 to Oct 4 statewide — one date for all of North Dakota would be off by weeks for Bismarck. Once you know Bismarck's freeze date, use it to shut down your sprinklers and winterize a boat too.

Other winter jobs in Bismarck

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

Sprinklers → Sep 29Frozen pipes → Sep 16Ice dams → Sep 15Car battery → Oct 9Snow blower → Sep 24Sump pump → May 10Boat → Oct 2Motorcycle → Sep 30

See the full Bismarck 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 Bismarck?
Wait until the last spring freeze has passed, which averages near May 10 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 Bismarck 2.4 Nnw, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.