Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for 85145 — Red Rock, AZ

ZIP code 85145 (Red Rock, Pinal County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is February 6 and the first fall frost December 9.

Where ZIP 85145 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone9a20 to 25 °F
Coldest night−6.7 to −3.9 °C
Last frostFeb 6
First frostDec 9
2012 zone9b

Was 9b on the 2012 map — half a zone colder now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Red Rock, AZ…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Red Rock, AZ

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 6median — 50% chance of a later frost
Safe for tender plantsMarch 5only 10% chance of frost after
First fall frostDecember 9median — 10% chance by Nov 22
Growing season308 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 14 and returns around December 19.

From the NOAA station Picacho 8 Se, AZ — 7 miles away, elevation 1,982 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 85145

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Dec 26 – Jan 9
SpinachSow outdoors · Dec 26 – Jan 16
Broccoli, cabbageStart indoors · Nov 28 – Dec 12
Broccoli, cabbageTransplant · Jan 16 – Jan 30
Onion setsPlant outdoors · Jan 9 – Jan 23
PotatoesPlant outdoors · Jan 16 – Jan 30
LettuceSow outdoors · Jan 9 – Jan 23
Carrots, beetsSow outdoors · Jan 16 – Jan 30
TomatoesStart indoors · Dec 12 – Dec 26
TomatoesTransplant · Feb 13 – Feb 27
Peppers, eggplantStart indoors · Nov 28 – Dec 12
Peppers, eggplantTransplant · Feb 20 – Mar 6
BeansSow outdoors · Feb 13 – Feb 27
Sweet cornSow outdoors · Feb 13 – Feb 27
Cucumbers, squashSow outdoors · Feb 13 – Feb 27
Fall lettuce, spinachSow outdoors · Oct 14 – Oct 28
GarlicPlant cloves · Nov 25 – Dec 30
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 6) and first fall frost (Dec 9) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 85145 came on Jan 25 — about the same time as the 1991–2020 average (Jan 26).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 9a in Arizona

492 plants native to the lower 48 states, recorded in Arizona, and rated by the USDA to survive 20 °F or colder — the bottom of zone 9a. Each links to its USDA PLANTS profile.

Trees 26

Arizona cypress50 ft · blooms spring · low shade tolerance · to −23 °FArizona madrone30 ft · blooms late spring · high shade tolerance · to −4 °FArizona sycamore80 ft · blooms early spring · high shade tolerance · to −8 °FArizona walnut50 ft · blooms late spring · high shade tolerance · to −33 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fblue spruce100 ft · blooms late spring · medium shade tolerance · to −38 °F

Shrubs 109

alderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °FAmerican tarwort3 ft · blooms late spring · high shade tolerance · to −23 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °FApache plume6 ft · blooms late spring · high shade tolerance · to −23 °Fbig sagebrush4 ft · blooms mid summer · high shade tolerance · to −43 °F

Wildflowers & perennials 197

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °FAmerican century plant6 ft · blooms indeterminate · high shade tolerance · to 12 °F

Grasses 151

alkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Fanalogue sedge1.5 ft · blooms late spring · medium shade tolerance · to −38 °FArizona cottontop4 ft · blooms late summer · high shade tolerance · to −13 °FArizona fescue2 ft · blooms late spring · high shade tolerance · to −23 °F

Vines 1

western white clematis1 ft · blooms mid summer · medium shade tolerance · to −38 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Red Rock, AZ.

Soil in Red Rock, AZ

The soil mapped at the center of ZIP 85145 is Gilman — fine sandy loam, well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding
pH8.0alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter0.25%low — add compost
Hydrologic groupAwater soaks in fast
Farmland classPrime farmland if irrigated and either protected from flooding or not frequently flooded during the growing seasonUSDA classification

Map unit: Gilman fine sandy loam, 0 to 2 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 85145; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Red Rock, AZ

Summer high104 °Faverage high, June
Winter low40 °Faverage low, December
Hot days176days a year at 90 °F or more
Freezing nights10nights a year at 32 °F or less
Growing degree days8,248base 50 °F — the season’s usable heat
Longest day14 h 17 mindaylight on June 21
Shortest day10 h 00 mindaylight on December 21
Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb
Precipitation9.9 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°110°32 °FJanuary: average high 67 °F, low 41 °F 67°41° JanFebruary: average high 71 °F, low 43 °F 71°43° FebMarch: average high 78 °F, low 48 °F 78°48° MarApril: average high 86 °F, low 54 °F 86°54° AprMay: average high 95 °F, low 63 °F 95°63° MayJune: average high 104 °F, low 72 °F 104°72° JunJuly: average high 104 °F, low 78 °F 104°78° JulAugust: average high 103 °F, low 78 °F 103°78° AugSeptember: average high 99 °F, low 72 °F 99°72° SepOctober: average high 89 °F, low 60 °F 89°60° OctNovember: average high 76 °F, low 49 °F 76°49° NovDecember: average high 66 °F, low 40 °F 66°40° Dec

Precipitation by month inches

0″1″2″January: 1.01 in precipitation 1.0 JanFebruary: 1.15 in precipitation 1.1 FebMarch: 0.90 in precipitation 0.9 MarApril: 0.28 in precipitation 0.3 AprMay: 0.22 in precipitation 0.2 MayJune: 0.20 in precipitation 0.2 JunJuly: 1.26 in precipitation 1.3 JulAugust: 1.86 in precipitation 1.9 AugSeptember: 0.92 in precipitation 0.9 SepOctober: 0.49 in precipitation 0.5 OctNovember: 0.51 in precipitation 0.5 NovDecember: 1.15 in precipitation 1.1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Picacho 8 Se, AZ (7 mi away); precipitation: Picacho 8 Se, AZ (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

5 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

851419a
Picacho, AZ · 7 mi
856539b
Marana, AZ · 10 mi
851319a
Eloy, AZ · 13 mi
856589b
Marana, AZ · 14 mi
856549b
Rillito, AZ · 16 mi
856529b
Cortaro, AZ · 18 mi
851239a
Arizona City, AZ · 21 mi
857439b
Tucson, AZ · 21 mi

Arizona planting zones →

Questions about 85145

What planting zone is ZIP code 85145?

ZIP code 85145 (Red Rock, AZ) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in Red Rock, AZ?

The median last spring frost (32 °F) near 85145 is February 6; after March 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Picacho 8 Se station.

When is the first frost in Red Rock, AZ?

The median first fall frost near 85145 is December 9, giving a median frost-free growing season of 308 days.

When should I plant tomatoes in 85145?

Start tomato seeds indoors around Dec 12 – Dec 26 and set transplants outside around Feb 13 – Feb 27, one to three weeks after the median last frost.

How much rain and snow does 85145 get?

About 9.9 inches of precipitation a year (NOAA 1991–2020 normals, Picacho 8 Se station).

How hot do summers get in Red Rock, AZ?

The average high peaks at 104 °F in June, with about 176 days a year at 90 °F or more.

What kind of soil does 85145 have?

The USDA soil survey maps Gilman at the center of ZIP 85145: fine sandy loam, well drained, pH about 8.0 (alkaline).

Did spring come early in Red Rock, AZ in 2026?

Spring leaf-out near 85145 came on Jan 25 in 2026, about the same as the 1991–2020 average (Jan 26), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Red Rock, AZ?

Short-day onions: the longest day near 85145 is 14 h 17 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.

Did the zone for 85145 change?

Yes. The 2012 USDA map put 85145 in zone 9b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.