Freeze numbers for Victorville, Hesperia, El Mirage and Barstow, when to shut down, and how to drain and protect valves, pipe and the backflow preventer.
Get a Free Irrigation EstimateYes, sprinklers in Hesperia, Victorville and Apple Valley need winter protection. Victorville averages about 54 nights a year at or below 32°F and its median first freeze is November 11, so have the system shut down or protected by early November. The job is four steps: shut off the irrigation water, set the controller to off or rain mode, drain the lines, and insulate the above-ground pipe, valves and backflow preventer without covering the backflow’s air vent.
Most winterizing guides are written for places with long, hard winters. The High Desert is different. We get dozens of freezing nights, but January afternoons average about 59°F in Liberty Utilities’ Apple Valley climate data (Liberty water supply assessment), and water districts here still expect some winter watering during daytime hours. So you have two choices: shut the system down for winter, or keep it running on a short daytime schedule with every above-ground part protected. This guide covers both, using NOAA climate normals, Rain Bird’s homeowner instructions, and what Hesperia, Liberty Utilities and the Mojave Water Agency tell their customers.
Yes, and how often depends on where you live. These are NOAA 1991-2020 normals for four High Desert stations (NOAA NCEI):
| NOAA station | Nights a year at or below 32°F | Dec to Feb freeze nights | Chance of 24°F / 20°F in a year | Median first fall freeze |
|---|---|---|---|---|
| Victorville | 53.7 | 41.9 | 96.6% / 59.3% | Nov 11 (1 year in 10 by Oct 27) |
| Hesperia 2E | 32.1 | 26.4 | 57.2% / 10.3% | Dec 1 |
| El Mirage (west side, toward Adelanto and Phelan) | 70.5 | 52.4 | 98.7% / 70.3% | Nov 12 |
| Barstow | 31.8 | 27.2 | 81.1% / 33.1% | Nov 23 |
At Victorville, December averages 17.2 freezing nights and January 16.1 (NOAA monthly normals). That is a lot of nights for water to sit in an above-ground pipe. Water expands about 9% when it freezes (USGS), and Rain Bird notes that valves installed below ground are less likely to freeze than above-ground models (Rain Bird valve guide). The parts most at risk are the ones you can see: anti-siphon valves, the backflow preventer, and exposed supply pipe.
Notice the spread. Hesperia 2E freezes about 32 nights a year and El Mirage about 70. A cold low spot or an open lot on the west side can behave more like El Mirage than like town.
In the fall: before the first freeze. Victorville’s median first freeze is November 11, and in 1 year out of 10 it comes by October 27 (NOAA). That makes late October to early November a sensible target for most of the Victor Valley. The City of Hesperia puts it simply: it is always cheaper and more convenient to winterize during warm weather (City of Hesperia).
In the spring: the median last freeze is March 18 at Victorville, February 28 at Hesperia 2E and March 21 at El Mirage. One year in ten, a freeze still comes after April 12 at Victorville, April 3 at Hesperia 2E and April 22 at El Mirage. Keep insulation on the backflow preventer until your area is past those dates.
Station-by-station frost dates and what they mean for planting are in our High Desert frost dates guide. The month-by-month list of yard jobs, including this one, is in the High Desert yard care calendar.
Liberty Utilities tells Apple Valley customers that during winter you typically do not need to water outdoors, as plant growth is usually on hold until February, and that the water supply should be shut off to prevent freeze damage to your sprinkler system (Liberty watering recommendations).
If you keep watering, water in the warm part of the day. Liberty says 9 a.m. to 3 p.m. in winter. Victorville sets 9 a.m. to 3 p.m. from October to May (Victorville), Hesperia recommends the same window for October to May (Hesperia), and Phelan Pinon Hills CSD uses it from November to May (PPHCSD). The Mojave Water Agency brochure says to water during the warmer part of the day from November to April to prevent water from freezing on your landscape (MWA).
Even if you keep watering, the above-ground parts still need insulation, because the water sits in them overnight. Cut run times way down too. Our sprinkler timer guide has month-by-month seasonal adjust starting points.
These steps follow Rain Bird’s homeowner winterization instructions (Rain Bird), with the City of Hesperia’s local advice added where it applies.
University of Arizona Extension says winterizing a drip system may be necessary in cold areas (UA Extension AZ1392). Drip lines themselves are usually buried or under mulch, so the exposed parts are the ones at the valve: the filter, the pressure regulator, and the valve itself. We did not find manufacturer drip winterizing steps, so treat this as general practice: drain those parts or insulate them along with the valve, and follow the same shut-off and controller steps above.
Winter water demand is low anyway. Liberty’s figures put December reference ET at 2.02 inches, against 9.53 inches in July (Liberty water supply assessment). If you do run drip in winter, stick to your district’s daytime winter hours.
Once your area is past its late-freeze date (see above), turning the system back on is mostly the winter steps in reverse:
If you find cracked valves or a split backflow preventer, that is a repair, and it is the kind of work Monarch’s irrigation team does. Our irrigation cost guide covers what goes into the price. More on the whole system is in the High Desert irrigation guide.
Yes. NOAA 1991-2020 normals show about 54 nights a year at or below 32 degrees at Victorville, and a night of 20 degrees or colder in about 6 years out of 10. El Mirage, on the west side, averages about 70 freezing nights.
Before the first freeze. The median first freeze at Victorville is November 11, and 1 year in 10 it comes by October 27, according to NOAA. Late October to early November is a sensible target.
Yes, during the day. Victorville sets 9 a.m. to 3 p.m. from October to May, Hesperia recommends that window, and Liberty Utilities says to water only between 9 a.m. and 3 p.m. in winter. Keep above-ground parts insulated either way.
Not always. Rain Bird lists manual drain valves, automatic drain valves and compressed-air blowout as the three ways to drain a system. It recommends a local irrigation specialist for blowouts because of the safety risks.
The median last freeze is March 18 at Victorville and February 28 at Hesperia 2E, but NOAA shows a 1 in 10 chance of a freeze after April 3 to April 22 depending on the station. Keep the backflow preventer insulated until then.
We checked every number on this page against the public sources below. If a rule or date changes, the agency page is the final word.
Monarch repairs and rebuilds sprinkler and drip systems across the High Desert, including valve manifolds and backflow replacements. Get a free estimate and a straight answer on whether you need a repair or a better layout.
Get a Free Irrigation EstimateOr call (760) 792-7627
