FrostList

When to Winterize Sprinklers in Des Plaines, IL

ON TRACK119 days until first 28°F freezeNov 7

In a typical year, winterize your sprinkler system in Des Plaines by October 28. The median first 28°F hard freeze at Des Plaines's NOAA station is November 7 (1991–2020 normals); one year in ten it arrives as early as October 27. The early-to-late range spans roughly 26 days, so treat the median as a midpoint, not a promise.

OUTLOOK

Typical first first 28°F freeze near Nov 7; local deadline about Oct 28. The live 10-day outlook loads here.

Local freeze dates for Des Plaines

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Oct 15Oct 28Nov 11
28°F (hard freeze)Oct 27Nov 7Nov 22
24°F (severe)Nov 3Nov 17Dec 2

NOAA station: Chicago Ohare Intl AP · 3.7 mi away · 658 ft elevation.

The reference station for Des Plaines is Chicago Ohare Intl AP (3.7 mi, 658 ft). First freeze there: 32°F by Oct 28, 28°F by Nov 7, 24°F by Nov 17. That hard freeze has landed anywhere from Oct 27 to Nov 22, a swing of roughly 26 days. Spring's last 32°F freeze clears around Apr 16. Snowfall averages 38 inches a year, first reaching an inch near November.

Des Plaines usually sees its first 32°F night about Oct 28, with the first 28°F hard freeze close behind near Nov 7. The 32°F date swings from Oct 15 at its earliest to Nov 11 at its latest, near 27 days. The last spring freeze averages Apr 16 and as late as May 1, which sets the safe window for reopening outdoor water and de-winterizing gear. About 38 inches of snow a year is enough to justify servicing the snow blower and watching the eaves.

Your sprinklers checklist

  1. Shut off the irrigation water supply at the main valve and, if you have one, the dedicated sprinkler shutoff inside the house.
  2. Turn off the controller or set it to the "rain" mode so valves do not open while the system is dry.
  3. Drain the mainline using the manual, automatic, or blow-out method your system was built for; most pros prefer a blow-out.
  4. Connect a compressor to the blow-out port through a proper adapter and run 40–80 psi, one zone at a time, until the heads mist and clear.
    Helpful gear: Air compressor blow-out adapter — Recommended pick
  5. Insulate the backflow preventer and any above-ground valves; this brass assembly is usually the first part to crack.
    Helpful gear: Insulated backflow preventer cover — Recommended pick
  6. Cap outdoor hose bibs with foam covers after the hoses come off so the last exposed fittings stay protected.
    Helpful gear: Foam outdoor faucet covers — Recommended pick
  7. Open the backflow test cocks a quarter turn so any trapped water has room to expand.
  8. Log the date and the psi you used; you will want the reference next fall.

What to have on hand

Air compressor blow-out adapter
Quick-connect fitting that mates a shop compressor to your irrigation line.
Recommended pick
Insulated backflow preventer cover
Pouch that shields the above-ground backflow valve from early frost.
Recommended pick
Foam outdoor faucet covers
Slip-on domes that protect hose bibs after you drain them.
Recommended pick
Portable air compressor
A modest pancake unit moves enough air to clear most home zones.
Recommended pick

What this means locally

Against its neighbors, Des Plaines (first freeze Nov 7) runs close to Park Ridge (Nov 7) and close to Mount Prospect (Nov 7). Across Illinois, local prep deadlines in our data range from Oct 14 to Nov 5, so a statewide rule of thumb would miss Des Plaines by weeks. In Des Plaines, that same cold is your cue to protect your indoor pipes and winterize an RV if you own one.

Other winter jobs in Des Plaines

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

Frozen pipes → Oct 15Ice dams → Oct 16Car battery → Nov 7Snow blower → Oct 25Sump pump → Apr 16RV → Oct 28Boat → Oct 31Motorcycle → Oct 28

See the full Des Plaines winter checklist, in order →

Frequently asked questions

What temperature freezes sprinkler pipes?
Standing water in shallow lines and the backflow assembly can start to freeze once air temperatures drop into the mid-20s for several hours. Buried mains are slower, but the exposed brass backflow preventer and above-ground valves are the parts that crack first, which is why the deadline is tied to the first 28°F freeze, not the first frost.
Do I need to blow out my sprinklers or just drain them?
It depends on how the system was installed. Manual or automatic drains work if the lines were pitched to low points. Most irrigation pros recommend a compressed-air blow-out because it clears water that drains miss, especially in flat yards. If you are unsure how your system drains, a blow-out is the safer choice.
What happens if I don't winterize my sprinkler system?
Water left in the lines expands as it freezes and can split the backflow preventer, crack valves, or break fittings. Repairs to a backflow assembly commonly run more than the cost of a blow-out. The damage often is not visible until you turn the system on in spring and find leaks.
How much does a sprinkler blowout cost?
A professional blow-out typically costs somewhere in the range of a modest service call, depending on the number of zones and your region. Buying an adapter and using your own compressor costs less over time, but you need enough air volume to clear each zone. Prices rise once the first freeze warnings appear, so book early.
When should I turn my sprinklers back on in Des Plaines?
Wait until the last spring freeze has passed, which averages around Apr 16 here in the 1991–2020 normals. Turning the system on too early risks refreezing a charged line. Open the main slowly to avoid a pressure surge, then walk each zone to check for winter damage before you rely on the schedule.
Can I winterize sprinklers myself?
Draining and insulating are within reach for most homeowners. A blow-out is doable if you own a compressor that moves enough air and you use a proper adapter, working one zone at a time at safe pressure. If your system lacks a clear blow-out port or you are not confident, hiring a pro once is a reasonable call.

Data: NOAA 1991–2020 normals via Chicago Ohare Intl AP, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.