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

Planting zone for 85620 — Naco, AZ

ZIP code 85620 (Naco, Cochise County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is April 1 and the first fall frost November 10.

Where ZIP 85620 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.

Zone8b15 to 20 °F

Coldest night−9.4 to −6.7 °C

Last frostApr 1

First frostNov 10

2012 zone8b

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 8b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Naco, 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 Naco, AZ

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 1median — 50% chance of a later frost

Safe for tender plantsApril 20only 10% chance of frost after

First fall frostNovember 10median — 10% chance by Oct 25

Growing season222 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 13 and returns around November 24.

From the NOAA station Bisbee 1wnw, AZ — 7 miles away, elevation 5,561 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 85620

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 18 – Mar 4

SpinachSow outdoors · Feb 18 – Mar 11

Broccoli, cabbageStart indoors · Jan 21 – Feb 4

Broccoli, cabbageTransplant · Mar 11 – Mar 25

Onion setsPlant outdoors · Mar 4 – Mar 18

PotatoesPlant outdoors · Mar 11 – Mar 25

LettuceSow outdoors · Mar 4 – Mar 18

Carrots, beetsSow outdoors · Mar 11 – Mar 25

TomatoesStart indoors · Feb 4 – Feb 18

TomatoesTransplant · Apr 8 – Apr 22

Peppers, eggplantStart indoors · Jan 21 – Feb 4

Peppers, eggplantTransplant · Apr 15 – Apr 29

BeansSow outdoors · Apr 8 – Apr 22

Sweet cornSow outdoors · Apr 8 – Apr 22

Cucumbers, squashSow outdoors · Apr 8 – Apr 22

Fall lettuce, spinachSow outdoors · Sep 15 – Sep 29

GarlicPlant cloves · Oct 27 – Dec 1

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 1) and first fall frost (Nov 10) 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 85620 came on Jan 31 — 3 days earlier than the 1991–2020 average (Feb 3).

average
Feb 32026
Jan 31

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 8b in Arizona

482 plants native to the lower 48 states, recorded in Arizona, and rated by the USDA to survive 15 °F or colder — the bottom of zone 8b. 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 Naco, AZ.

Soil in Naco, AZ

The soil mapped at the center of ZIP 85620 is Riveroad — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH7.9alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Riveroad and Ubik soils, 0 to 5 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 85620; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Naco, AZ

Summer high89 °Faverage high, June

Winter low32 °Faverage low, January

Hot days36days a year at 90 °F or more

Freezing nights63nights a year at 32 °F or less

Growing degree days4,228base 50 °F — the season’s usable heat

Longest day14 h 11 mindaylight on June 21

Shortest day10 h 06 mindaylight on December 21

Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb

Precipitation17.1 inper year, rain and melted snow

Snowfall3 inper year; 1 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Bisbee 1wnw, AZ (7 mi away); precipitation: Bisbee 1wnw, AZ (7 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.

Sierra Vista, AZ · 19 mi

856358b

Sierra Vista, AZ · 20 mi

856178b

Mc Neal, AZ · 21 mi

856268a

Pirtleville, AZ · 22 mi

Arizona planting zones →

Questions about 85620

What planting zone is ZIP code 85620?

ZIP code 85620 (Naco, AZ) is in USDA hardiness zone 8b on the 2023 map: the coldest night of an average winter reaches 15 to 20 °F (−9.4 to −6.7 °C).

When is the last frost in Naco, AZ?

The median last spring frost (32 °F) near 85620 is April 1; after April 20 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Bisbee 1wnw station.

When is the first frost in Naco, AZ?

The median first fall frost near 85620 is November 10, giving a median frost-free growing season of 222 days.

When should I plant tomatoes in 85620?

Start tomato seeds indoors around Feb 4 – Feb 18 and set transplants outside around Apr 8 – Apr 22, one to three weeks after the median last frost.

How much rain and snow does 85620 get?

About 17.1 inches of precipitation a year and 3 inches of snowfall (NOAA 1991–2020 normals, Bisbee 1wnw station).

How hot do summers get in Naco, AZ?

The average high peaks at 89 °F in June, with about 36 days a year at 90 °F or more.

What kind of soil does 85620 have?

The USDA soil survey maps Riveroad at the center of ZIP 85620: silt loam, well drained, pH about 7.9 (alkaline).

Did spring come early in Naco, AZ in 2026?

Spring leaf-out near 85620 came on Jan 31 in 2026, 3 days earlier than the 1991–2020 average (Feb 3), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Naco, AZ?

Short-day onions: the longest day near 85620 is 14 h 11 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.