Hard freezes, spring wind, 9-inch July water demand and six different water districts. The basics for sprinklers and drip in Hesperia, Victorville, Apple Valley and nearby.
Get a Free Irrigation EstimateHigh Desert irrigation comes down to four things: freezes hard enough to crack above-ground parts, plant water demand in July that is about four times January’s, wind that blows spray off target, and watering rules that change by water district. Protect the system from early November into April, change your run times with the month, use drip for shrubs and trees, and set your days to match your district.
Most irrigation advice online is written for places that do not freeze, or for lawns in wetter climates. Out here a July timer setting will drown plants in January, and a backflow preventer left full of water can split on a 20°F night. Every number comes from NOAA, the Liberty Utilities water supply study for Apple Valley, UC and Arizona extension publications, manufacturer manuals, or the water districts themselves. The source list is at the bottom.
There is no single freeze number for the High Desert. NOAA’s 1991-2020 normals show big differences between stations only a few miles apart (NOAA NCEI):
| NOAA station | Nights a year at or below 32°F | Chance of a 20°F night in a year | Median first fall freeze | Median last spring freeze | 1 year in 10, a freeze after |
|---|---|---|---|---|---|
| Victorville | 53.7 | 59.3% | Nov 11 | Mar 18 | Apr 12 |
| Hesperia 2E | 32.1 | 10.3% | Dec 1 | Feb 28 | Apr 3 |
| El Mirage (west side, toward Adelanto and Phelan) | 70.5 | 70.3% | Nov 12 | Mar 21 | Apr 22 |
Why it matters: water expands about 9% when it freezes (USGS). California homes commonly use anti-siphon valves, and Rain Bird says those must sit at least 6 inches above the highest sprinkler head they serve, so the valve bodies are above ground. Rain Bird also notes in-line valves installed below ground are less likely to freeze than above-ground models (Rain Bird valve guide). The City of Hesperia lists irrigation control valves among the pipes at risk in winter (City of Hesperia).
Plan on having freeze protection in place by early November. How to do it is in our guides to winterizing sprinklers in the High Desert and backflow preventer freeze protection. For planting dates by town, see the High Desert frost dates guide.
Reference evapotranspiration (ETo) is the water a standard grass surface loses in a month. It is the number irrigation designers use to size run times. Liberty Utilities published monthly ETo for its Apple Valley service area in its October 2025 water supply assessment (Liberty Utilities, Table 2-1). The last column is our own math, not a Liberty or district schedule: each month’s ETo divided by July’s.
| Month | ETo (inches) | Rain (inches) | Our estimate: timer % if July = 100% |
|---|---|---|---|
| January | 2.22 | 0.95 | 23% |
| February | 3.01 | 1.01 | 32% |
| March | 4.98 | 0.78 | 52% |
| April | 6.48 | 0.36 | 68% |
| May | 7.98 | 0.11 | 84% |
| June | 9.11 | 0.04 | 96% |
| July | 9.53 | 0.14 | 100% |
| August | 8.80 | 0.19 | 92% |
| September | 6.55 | 0.22 | 69% |
| October | 4.52 | 0.32 | 47% |
| November | 2.74 | 0.48 | 29% |
| December | 2.02 | 0.87 | 21% |
How to use it: set run times that keep your plants healthy in July, then use your controller’s seasonal adjust to drop to the percentage for the month. Treat those percentages as a starting point and check them against your plants. Step-by-step seasonal adjust settings for Rain Bird and Hunter are in our sprinkler timer guide.
Plants do not all need the full ETo. The WUCOLS method from UC Cooperative Extension and the Department of Water Resources puts Victorville, Apple Valley and Barstow in Region 5, High and Intermediate Desert, and groups plants by need: high 70 to 90% of ETo, moderate 40 to 60%, low 10 to 30%, and very low under 10% (WUCOLS). Most plants on our drought-tolerant plant list fall in the low groups.
Spring wind is the other High Desert problem. Liberty Utilities says to avoid running sprinklers on windy days in spring (Liberty watering recommendations), Phelan Pinon Hills CSD says to avoid watering on windy days (PPHCSD), and the Mojave Water Agency’s conservation brochure says to avoid watering when it is windy or rainy (MWA brochure). Spray that blows onto a sidewalk or street also counts as runoff, and Victorville, Hesperia, Liberty and Phelan Pinon Hills all prohibit runoff onto walks and roads.
Puts water at the root zone of shrubs, trees and beds. University of Arizona Extension says drip needs about 20 psi and a pressure regulator, since household supply runs 50 to 75 psi, and lateral lines are generally buried in the soil (UA Extension AZ1392). Emitters that pop off are usually a pressure problem, and mineral crust can be soaked off in vinegar (UA drip tune-up).
Still the tool for real lawns. Spray zones are the ones district rules are written around. Liberty’s recommendations cap sprinklers at 10 minutes per station per day (Liberty), and wind drift turns spray into runoff. Anti-siphon valves feeding those zones sit above ground and need winter protection.
Drip also gets a break on the rules in some districts. Victorville’s page says drip irrigation systems are exempt from the watering schedules, and Liberty exempts drip-only zones (Liberty drought page). Hesperia and Adelanto do not say either way on the pages we checked.
Monarch’s irrigation and drip work includes converting spray beds to drip, often alongside artificial turf or rockscape. What drives the cost of that kind of job is covered in our irrigation cost guide.
Your rules come from your water provider, not your city name. A few Apple Valley homes are on Golden State Water, not Liberty. This is the short version. The full table with every source and the date each page was last updated is in our High Desert watering schedules guide.
| Provider | Sprinkler days | Drip |
|---|---|---|
| Victorville Water | Even addresses Tue, Thu, Sat. Odd addresses Wed, Fri, Sun. | Exempt |
| Hesperia Water District | Any day, with recommended hours | Not stated |
| Liberty Utilities, Apple Valley | Up to 3 days. Even Mon, Wed, Sat. Odd Tue, Thu, Sun. (An older Liberty page still shows a 2-day Stage 2 schedule.) | Drip-only zones exempt |
| Golden State Water, Apple Valley | Up to 3 days. Even Sun, Wed, Fri. Odd Tue, Thu, Sat. | Not stated |
| Phelan Pinon Hills CSD | No set days. Hours only. No irrigation 48 hours after measurable rain. | Not stated |
| Adelanto | Even Tue, Thu. Odd Wed, Fri. No landscape watering Mondays or weekends. | Not stated |
Several of these pages conflict with each other or are years old. Confirm with your district before you reprogram your timer.
For the rest of the year’s yard work, see the High Desert yard care calendar.
It depends on where you are. NOAA 1991-2020 normals show about 54 nights a year at or below 32 degrees at Victorville, about 32 at the Hesperia 2E station, and about 70 at El Mirage on the west side toward Adelanto and Phelan.
Liberty Utilities data for Apple Valley puts January ETo at 2.22 inches against 9.53 inches in July. By our math that is about 23% of July’s water, so a controller set to 100% in July would run near 20 to 25% in December and January. Adjust from there by watching your plants.
In Victorville, yes: the city says drip irrigation systems are exempt from the watering schedules. Liberty Utilities in Apple Valley exempts drip-only zones. Hesperia and Adelanto do not address drip on the pages we checked, so ask your district.
In summer, water at night. Victorville sets 10 p.m. to 6 a.m. from June to September. In winter, water during the day. Victorville sets 9 a.m. to 3 p.m. from October to May, and the Mojave Water Agency says to water during the warmer part of the day from November to April so water does not freeze on the landscape.
Use drip for shrubs, trees and planted beds, and keep spray or rotors for lawn areas. Drip needs a pressure regulator because it runs at about 20 psi while house pressure is often 50 to 75 psi, according to University of Arizona Extension.
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 installs and repairs sprinkler and drip systems across the High Desert, including drip conversions for rock and turf yards and valve manifolds laid out so they are easy to protect in winter. Get a free estimate and a straight answer on what your system needs.
Get a Free Irrigation EstimateOr call (760) 792-7627
