FrostList

When to Winterize Sprinklers in Houston, TX

SEASON PASSED178 days until first 28°F freezeJan 5

Aim to winterize your sprinkler system in Houston by December 26, roughly a week and a half before the median first 28°F freeze of January 5, which one fall in ten shows up by December 8. The early-to-late range spans roughly 63 days, so treat the median as a midpoint, not a promise.

OUTLOOK

Typical first first 28°F freeze near Jan 5; local deadline about Dec 26. The live 10-day outlook loads here.

Local freeze dates for Houston

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Nov 27Dec 25Jan 21
28°F (hard freeze)Dec 8Jan 5Feb 9
24°F (severe)Dec 25Jan 10Feb 14

NOAA station: Houston-Port · 5.5 mi away · 19 ft elevation.

Numbers for Houston come from Houston-Port, 5.5 miles away at 19 feet, where the medians fall 32°F by Dec 25, 28°F by Jan 5, 24°F by Jan 10. The 28°F freeze has come as early as Dec 8 and as late as Feb 9, a 63-day spread. Spring's last 32°F freeze clears around Feb 2.

Houston usually sees its first 32°F night about Dec 25, with the first 28°F hard freeze close behind near Jan 5. The 32°F date swings from Nov 27 at its earliest to Jan 21 at its latest, near 55 days. The last spring freeze averages Feb 2 and as late as Mar 5, which sets the safe window for reopening outdoor water and de-winterizing gear. Snow barely registers here; the freeze date, around Feb 2, is the one that matters.

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

Houston freezes close to Pasadena (Jan 5) and later than Missouri City (Jan 1) — a reminder that even nearby towns differ by days. Statewide, Texas prep dates run Oct 27 through Dec 29, which is why Houston gets its own number rather than a Texas-wide average. The same freeze also decides when to protect your indoor pipes and winterize an RV if you own one.

Other winter jobs in Houston

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

Frozen pipes → Nov 27Car battery → Jan 5Sump pump → Feb 2RV → Dec 26Boat → Dec 29Motorcycle → Dec 25

See the full Houston 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 Houston?
Wait until the last spring freeze has passed, which averages around Feb 2 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 Houston-Port, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.