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

Planting zone for 85539 — Miami, AZ

ZIP code 85539 (Miami, Gila County) is in USDA zone 8a: the coldest winter night averages 10 to 15 °F. The median last spring frost is February 24 and the first fall frost December 1.

Where ZIP 85539 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.

Zone8a10 to 15 °F

Coldest night−12.2 to −9.4 °C

Last frostFeb 24

First frostDec 1

2012 zone9a

Was 9a on the 2012 map — a full zone colder now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 8a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Miami, 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 Miami, AZ

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostFebruary 24median — 50% chance of a later frost

Safe for tender plantsMarch 18only 10% chance of frost after

First fall frostDecember 1median — 10% chance by Nov 15

Growing season279 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 30 and returns around December 13.

From the NOAA station Miami, AZ — 6 miles away, elevation 3,560 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 85539

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Jan 13 – Jan 27

SpinachSow outdoors · Jan 13 – Feb 3

Broccoli, cabbageStart indoors · Dec 16 – Dec 30

Broccoli, cabbageTransplant · Feb 3 – Feb 17

Onion setsPlant outdoors · Jan 27 – Feb 10

PotatoesPlant outdoors · Feb 3 – Feb 17

LettuceSow outdoors · Jan 27 – Feb 10

Carrots, beetsSow outdoors · Feb 3 – Feb 17

TomatoesStart indoors · Dec 30 – Jan 13

TomatoesTransplant · Mar 3 – Mar 17

Peppers, eggplantStart indoors · Dec 16 – Dec 30

Peppers, eggplantTransplant · Mar 10 – Mar 24

BeansSow outdoors · Mar 3 – Mar 17

Sweet cornSow outdoors · Mar 3 – Mar 17

Cucumbers, squashSow outdoors · Mar 3 – Mar 17

Fall lettuce, spinachSow outdoors · Oct 6 – Oct 20

GarlicPlant cloves · Nov 17 – Dec 22

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 24) and first fall frost (Dec 1) 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 85539 came on Feb 2 — 10 days earlier than the 1991–2020 average (Feb 12).

average
Feb 122026
Feb 2

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 8a in Arizona

472 plants native to the lower 48 states, recorded in Arizona, and rated by the USDA to survive 10 °F or colder — the bottom of zone 8a. 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 Miami, AZ.

Soil in Miami, AZ

The soil mapped at the center of ZIP 85539 is Lithic Argiustolls — extremely cobbly loam, well drained.

TextureExtremely cobbly loama good balance for most vegetables

pH7.2neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Lithic Argiustolls, Cumulic Haplustolls, rarely flooded, and Typic Ustorthents; warm mesic ustic mountains.

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 85539; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Miami, AZ

Summer high100 °Faverage high, July

Winter low35 °Faverage low, December

Hot days122days a year at 90 °F or more

Freezing nights25nights a year at 32 °F or less

Growing degree days6,464base 50 °F — the season’s usable heat

Longest day14 h 22 mindaylight on June 21

Shortest day9 h 56 mindaylight on December 21

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

Precipitation17.2 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: Miami, AZ (6 mi away); precipitation: Miami, AZ (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Roosevelt, AZ · 20 mi

851179b

Apache Junction, AZ · 23 mi

851189b

Gold Canyon, AZ · 25 mi

Arizona planting zones →

Questions about 85539

What planting zone is ZIP code 85539?

ZIP code 85539 (Miami, AZ) is in USDA hardiness zone 8a on the 2023 map: the coldest night of an average winter reaches 10 to 15 °F (−12.2 to −9.4 °C).

When is the last frost in Miami, AZ?

The median last spring frost (32 °F) near 85539 is February 24; after March 18 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Miami station.

When is the first frost in Miami, AZ?

The median first fall frost near 85539 is December 1, giving a median frost-free growing season of 279 days.

When should I plant tomatoes in 85539?

Start tomato seeds indoors around Dec 30 – Jan 13 and set transplants outside around Mar 3 – Mar 17, one to three weeks after the median last frost.

How much rain and snow does 85539 get?

About 17.2 inches of precipitation a year (NOAA 1991–2020 normals, Miami station).

How hot do summers get in Miami, AZ?

The average high peaks at 100 °F in July, with about 122 days a year at 90 °F or more.

What kind of soil does 85539 have?

The USDA soil survey maps Lithic Argiustolls at the center of ZIP 85539: extremely cobbly loam, well drained, pH about 7.2 (neutral).

Did spring come early in Miami, AZ in 2026?

Spring leaf-out near 85539 came on Feb 2 in 2026, 10 days earlier than the 1991–2020 average (Feb 12), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Miami, AZ?

Intermediate onions: the longest day near 85539 is 14 h 22 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 85539 change?

Yes. The 2012 USDA map put 85539 in zone 9a; the 2023 map puts it in zone 8a. The newer map uses 1991–2020 data and more weather stations.