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

Planting zone for 85534 — Duncan, AZ

ZIP code 85534 (Duncan, Greenlee County) is in USDA zone 8a: the coldest winter night averages 10 to 15 °F. The median last spring frost is April 24 and the first fall frost October 25.

Where ZIP 85534 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 frostApr 24
First frostOct 25
2012 zone7b

Was 7b on the 2012 map — half a zone warmer 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 Duncan, 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 Duncan, AZ

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 24median — 50% chance of a later frost
Safe for tender plantsMay 8only 10% chance of frost after
First fall frostOctober 25median — 10% chance by Oct 11
Growing season183 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 7 and returns around November 2.

From the NOAA station Duncan, AZ — 2 miles away, elevation 3,662 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 85534

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 13 – Mar 27
SpinachSow outdoors · Mar 13 – Apr 3
Broccoli, cabbageStart indoors · Feb 13 – Feb 27
Broccoli, cabbageTransplant · Apr 3 – Apr 17
Onion setsPlant outdoors · Mar 27 – Apr 10
PotatoesPlant outdoors · Apr 3 – Apr 17
LettuceSow outdoors · Mar 27 – Apr 10
Carrots, beetsSow outdoors · Apr 3 – Apr 17
TomatoesStart indoors · Feb 27 – Mar 13
TomatoesTransplant · May 1 – May 15
Peppers, eggplantStart indoors · Feb 13 – Feb 27
Peppers, eggplantTransplant · May 8 – May 22
BeansSow outdoors · May 1 – May 15
Sweet cornSow outdoors · May 1 – May 15
Cucumbers, squashSow outdoors · May 1 – May 15
Fall lettuce, spinachSow outdoors · Aug 30 – Sep 13
GarlicPlant cloves · Oct 11 – Nov 15
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 24) and first fall frost (Oct 25) 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 85534 came on Feb 3 — 3 days earlier than the 1991–2020 average (Feb 6).

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).

Soil in Duncan, AZ

The soil mapped at the center of ZIP 85534 is Tapco — very cobbly clay loam, well drained.

TextureVery cobbly clay loamholds water and nutrients; slow to drain and warm up
pH7.9alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Tapco-Peloncillo association, 2 to 15 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 85534; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Duncan, AZ

Summer high98 °Faverage high, June
Winter low25 °Faverage low, January
Hot days130days a year at 90 °F or more
Freezing nights113nights a year at 32 °F or less
Growing degree days4,911base 50 °F — the season’s usable heat
Longest day14 h 18 mindaylight on June 21
Shortest day10 h 00 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation10.4 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°110°32 °FJanuary: average high 60 °F, low 25 °F 60°25° JanFebruary: average high 65 °F, low 29 °F 65°29° FebMarch: average high 73 °F, low 33 °F 73°33° MarApril: average high 81 °F, low 39 °F 81°39° AprMay: average high 89 °F, low 47 °F 89°47° MayJune: average high 98 °F, low 57 °F 98°57° JunJuly: average high 98 °F, low 66 °F 98°66° JulAugust: average high 96 °F, low 65 °F 96°65° AugSeptember: average high 91 °F, low 56 °F 91°56° SepOctober: average high 81 °F, low 43 °F 81°43° OctNovember: average high 69 °F, low 31 °F 69°31° NovDecember: average high 59 °F, low 25 °F 59°25° Dec

Precipitation by month inches

0″1″2″3″January: 0.94 in precipitation 0.9 JanFebruary: 0.84 in precipitation 0.8 FebMarch: 0.50 in precipitation 0.5 MarApril: 0.17 in precipitation 0.2 AprMay: 0.29 in precipitation 0.3 MayJune: 0.25 in precipitation 0.3 JunJuly: 1.68 in precipitation 1.7 JulAugust: 2.18 in precipitation 2.2 AugSeptember: 1.21 in precipitation 1.2 SepOctober: 0.71 in precipitation 0.7 OctNovember: 0.64 in precipitation 0.6 NovDecember: 1.00 in precipitation 1.0 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Duncan, AZ (2 mi away); precipitation: Duncan, AZ (2 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.

880517b
Mule Creek, NM · 23 mi
855408b
Morenci, AZ · 24 mi
855518b
Solomon, AZ · 24 mi
880557b
Redrock, NM · 24 mi
855468b
Safford, AZ · 25 mi
880287b
Cliff, NM · 33 mi
856058b
Bowie, AZ · 34 mi
880257b
Buckhorn, NM · 36 mi

Arizona planting zones →

Questions about 85534

What planting zone is ZIP code 85534?

ZIP code 85534 (Duncan, 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 Duncan, AZ?

The median last spring frost (32 °F) near 85534 is April 24; after May 8 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Duncan station.

When is the first frost in Duncan, AZ?

The median first fall frost near 85534 is October 25, giving a median frost-free growing season of 183 days.

When should I plant tomatoes in 85534?

Start tomato seeds indoors around Feb 27 – Mar 13 and set transplants outside around May 1 – May 15, one to three weeks after the median last frost.

How much rain and snow does 85534 get?

About 10.4 inches of precipitation a year (NOAA 1991–2020 normals, Duncan station).

How hot do summers get in Duncan, AZ?

The average high peaks at 98 °F in June, with about 130 days a year at 90 °F or more.

What kind of soil does 85534 have?

The USDA soil survey maps Tapco at the center of ZIP 85534: very cobbly clay loam, well drained, pH about 7.9 (alkaline).

Did spring come early in Duncan, AZ in 2026?

Spring leaf-out near 85534 came on Feb 3 in 2026, 3 days earlier than the 1991–2020 average (Feb 6), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Duncan, AZ?

Intermediate onions: the longest day near 85534 is 14 h 18 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 85534 change?

Yes. The 2012 USDA map put 85534 in zone 7b; the 2023 map puts it in zone 8a. The newer map uses 1991–2020 data and more weather stations.