- Tucson's average first freeze is around Dec. 3 and the average last freeze around Feb. 7, based on National Weather Service 1991-2020 normals.
- Wrap, drain or drip exposed pipes, have your backflow assembly tested each year as Tucson Water requires, and winterize the swamp cooler's water line.
- Cover frost-tender plants with cloth, not plastic, and take sheets off in the morning, per University of Arizona Cooperative Extension.
Tucson doesn’t get many freezing nights, but the few we get can be costly if a house isn’t ready. Based on the National Weather Service’s 1991 to 2020 normals, Tucson’s average first freeze of the fall comes around December 3, and the average last freeze comes around February 7. Some years it comes early. The earliest first freeze on record was October 16, 1899.
That makes early November a good time to spend an hour on the outside of your house. Here’s what’s worth checking.
Pipes and hose bibs
A lot of Tucson plumbing sits outside or close to it: hose bibs, irrigation lines, the line that feeds a swamp cooler, and pipes where they come up out of the ground. When the Weather Service issued a freeze warning for the Tucson metro area in January 2025, with lows of 25 to 32 degrees, its advice was simple: wrap exposed pipes, drain them, or let them drip slowly.
- Unhook garden hoses so water isn’t trapped at the faucet.
- Wrap exposed pipes now, before the first freeze warning, not the night of.
- Find your main water shutoff so you know where it is if a pipe ever splits.
The backflow device
Some Tucson homes have a backflow prevention assembly, an above-ground device that keeps water from a system like irrigation from flowing back into the drinking water. Tucson Water requires these assemblies to be tested every year by an approved certified tester. Because the device sits above ground, it’s one of the more exposed pieces of plumbing on the property. If you have one, ask your tester what freeze protection fits your specific device.
The swamp cooler
If you’re done with the cooler for the year, the University of Arizona’s Water Wise program recommends winterizing it once the weather cools. Turn off the power to the cooler before you work on it, then:
- Disconnect the water line from the cooler and blow the water out of it, so it can’t freeze.
- Drain and clean the tray at the bottom, let it dry, and check it for cracks.
- Cover the cooler. That protects it and keeps cold air from coming into the house.
Frost-tender plants
University of Arizona Cooperative Extension’s frost protection guide makes a few points worth knowing:
- Use cloth, not plastic. Frost cloth works best. Sheets or blankets give some protection.
- Cover all the way to the ground, and keep the cover off the leaves with a simple frame. Calm, clear nights are the riskiest, and the coldest point usually comes around daybreak.
- Take sheets and blankets off in the morning once it warms up. Left on all winter, they can do more harm than good.
- Keep plants watered. Dry plants are damaged more easily.
If you’re buying this winter
Winter is a good time to see how a house handles the cold. On a showing or at inspection, look at the exposed pipes, the hose bibs and the cooler. If the home has a backflow assembly, ask for the most recent annual test. These are small questions, and they’re easier to ask before closing than after.
If you’re selling this winter
A split pipe or cooler line in the middle of escrow is a hassle nobody needs. Run through this checklist before you list. If the home will sit empty while it’s on the market, decide ahead of time who will check on it after a hard freeze. It’s also one less thing for a buyer’s inspection to flag.
One easy next step
If you’re thinking about buying or selling in Tucson this winter and want a second set of eyes on a house, text me. If you’re still looking around, here are the newest Tucson-area listings, and my guide to owning a home in the Sonoran Desert covers the rest of the year.
Sources
- Tucson Freeze Dates, National Weather Service Tucson (1991-2020 normals)
- Freeze Warning, Tucson Metro Area, National Weather Service Tucson (Jan. 13, 2025)
- Backflow Prevention: Most Requested Information, City of Tucson, Tucson Water
- Water Saving Tips: Swamp Cooler Maintenance, University of Arizona Cooperative Extension, Water Wise
- Frost Protection (AZ1002), University of Arizona Cooperative Extension
I summarize these sources in my own words. If something here looks off, text me and I’ll check it.
Equal Housing Opportunity. This update is general information, not legal, tax or lending advice.