Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 85320 — Aguila, AZ

ZIP code 85320 (Aguila, Maricopa County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is March 17 and the first fall frost November 19.

Where ZIP 85320 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 frostMar 17

First frostNov 19

2012 zone9a

Same zone as on the 2012 map. 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 Aguila, 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 Aguila, AZ

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMarch 17median — 50% chance of a later frost

Safe for tender plantsApril 12only 10% chance of frost after

First fall frostNovember 19median — 10% chance by Nov 5

Growing season243 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 19 and returns around December 1.

From the NOAA station Aguila, AZ — 8 miles away, elevation 2,165 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 85320

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 3 – Feb 17

SpinachSow outdoors · Feb 3 – Feb 24

Broccoli, cabbageStart indoors · Jan 6 – Jan 20

Broccoli, cabbageTransplant · Feb 24 – Mar 10

Onion setsPlant outdoors · Feb 17 – Mar 3

PotatoesPlant outdoors · Feb 24 – Mar 10

LettuceSow outdoors · Feb 17 – Mar 3

Carrots, beetsSow outdoors · Feb 24 – Mar 10

TomatoesStart indoors · Jan 20 – Feb 3

TomatoesTransplant · Mar 24 – Apr 7

Peppers, eggplantStart indoors · Jan 6 – Jan 20

Peppers, eggplantTransplant · Mar 31 – Apr 14

BeansSow outdoors · Mar 24 – Apr 7

Sweet cornSow outdoors · Mar 24 – Apr 7

Cucumbers, squashSow outdoors · Mar 24 – Apr 7

Fall lettuce, spinachSow outdoors · Sep 24 – Oct 8

GarlicPlant cloves · Nov 5 – Dec 10

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 17) and first fall frost (Nov 19) 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 85320 came on Jan 21 — 7 days earlier than the 1991–2020 average (Jan 28).

average
Jan 282026
Jan 21

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.

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 Aguila, AZ.

Soil in Aguila, AZ

The soil mapped at the center of ZIP 85320 is Cellar — very gravelly fine sandy loam, well drained.

TextureVery gravelly fine sandy loamdrains and warms fast; dries out and needs more feeding

pH7.5slightly alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter0.75%low — add compost

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Cellar-Rock outcrop complex, low precipitation, 10 to 70 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 85320; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Aguila, AZ

Summer high101 °Faverage high, July

Winter low33 °Faverage low, December

Hot days145days a year at 90 °F or more

Freezing nights42nights a year at 32 °F or less

Growing degree days6,084base 50 °F — the season’s usable heat

Longest day14 h 24 mindaylight on June 21

Shortest day9 h 54 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation7.1 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

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

Nearby ZIP codes

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

853579a

Wenden, AZ · 18 mi

853909a

Wickenburg, AZ · 21 mi

853489a

Salome, AZ · 27 mi

853589a

Wickenburg, AZ · 30 mi

Arizona planting zones →

Questions about 85320

What planting zone is ZIP code 85320?

ZIP code 85320 (Aguila, 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 Aguila, AZ?

The median last spring frost (32 °F) near 85320 is March 17; after April 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Aguila station.

When is the first frost in Aguila, AZ?

The median first fall frost near 85320 is November 19, giving a median frost-free growing season of 243 days.

When should I plant tomatoes in 85320?

Start tomato seeds indoors around Jan 20 – Feb 3 and set transplants outside around Mar 24 – Apr 7, one to three weeks after the median last frost.

How much rain and snow does 85320 get?

About 7.1 inches of precipitation a year (NOAA 1991–2020 normals, Aguila station).

How hot do summers get in Aguila, AZ?

The average high peaks at 101 °F in July, with about 145 days a year at 90 °F or more.

What kind of soil does 85320 have?

The USDA soil survey maps Cellar at the center of ZIP 85320: very gravelly fine sandy loam, well drained, pH about 7.5 (slightly alkaline).

Did spring come early in Aguila, AZ in 2026?

Spring leaf-out near 85320 came on Jan 21 in 2026, 7 days earlier than the 1991–2020 average (Jan 28), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Aguila, AZ?

Intermediate onions: the longest day near 85320 is 14 h 24 min, so day-neutral types bulb best; long-day varieties may not bulb fully.