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

Planting zone for 86004 — Flagstaff, AZ

ZIP code 86004 (Flagstaff, Coconino County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is June 16 and the first fall frost September 19.

Where ZIP 86004 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.

Zone6b−5 to 0 °F

Coldest night−20.6 to −17.8 °C

Last frostJun 16

First frostSep 19

2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Flagstaff, 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 Flagstaff, AZ

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 16median — 50% chance of a later frost

Safe for tender plantsJune 29only 10% chance of frost after

First fall frostSeptember 19median — 10% chance by Aug 31

Growing season94 daysfrost-free, median

A hard freeze (28 °F) usually ends around June 5 and returns around September 28.

From the NOAA station Sunset Crater Nm, AZ — 9 miles away, elevation 6,982 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 86004

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · May 5 – May 19

SpinachSow outdoors · May 5 – May 26

Broccoli, cabbageStart indoors · Apr 7 – Apr 21

Broccoli, cabbageTransplant · May 26 – Jun 9

Onion setsPlant outdoors · May 19 – Jun 2

PotatoesPlant outdoors · May 26 – Jun 9

LettuceSow outdoors · May 19 – Jun 2

Carrots, beetsSow outdoors · May 26 – Jun 9

TomatoesStart indoors · Apr 21 – May 5

TomatoesTransplant · Jun 23 – Jul 7

Peppers, eggplantStart indoors · Apr 7 – Apr 21

Peppers, eggplantTransplant · Jun 30 – Jul 14

BeansSow outdoors · Jun 23 – Jul 7

Sweet cornSow outdoors · Jun 23 – Jul 7

Cucumbers, squashSow outdoors · Jun 23 – Jul 7

Fall lettuce, spinachSow outdoors · Jul 25 – Aug 8

GarlicPlant cloves · Sep 5 – Oct 10

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 16) and first fall frost (Sep 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 86004 came on Feb 23 — 19 days earlier than the 1991–2020 average (Mar 14).

average
Mar 142026
Feb 23

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 6b in Arizona

441 plants native to the lower 48 states, recorded in Arizona, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. 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 Flagstaff, AZ.

Soil in Flagstaff, AZ

The soil mapped at the center of ZIP 86004 is Wukoki — very gravelly loam, somewhat excessively drained.

TextureVery gravelly loama good balance for most vegetables

pH7.6slightly alkaline; most vegetables like 6.0–7.0

DrainageSomewhat excessively drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Wukoki-Wupatki very cindery loams, 15 to 60 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 86004; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Flagstaff, AZ

Summer high84 °Faverage high, July

Winter low12 °Faverage low, December

Hot days13days a year at 90 °F or more

Freezing nights215nights a year at 32 °F or less

Growing degree days1,758base 50 °F — the season’s usable heat

Longest day14 h 33 mindaylight on June 21

Shortest day9 h 46 mindaylight on December 21

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

Precipitation17 inper year, rain and melted snow

Snowfall49 inper year; 59 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: Sunset Crater Nm, AZ (9 mi away); precipitation: Sunset Crater Nm, AZ (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

860037a

Flagstaff, AZ · 14 mi

860357a

Leupp, AZ · 19 mi

860026a

Flagstaff, AZ · 20 mi

860016a

Flagstaff, AZ · 22 mi

860056a

Flagstaff, AZ · 25 mi

860155b

Bellemont, AZ · 27 mi

860166b

Gray Mountain, AZ · 30 mi

860386b

Mormon Lake, AZ · 33 mi

All 5 ZIP codes in Flagstaff → · Arizona planting zones →

Questions about 86004

What planting zone is ZIP code 86004?

ZIP code 86004 (Flagstaff, AZ) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Flagstaff, AZ?

The median last spring frost (32 °F) near 86004 is June 16; after June 29 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Sunset Crater Nm station.

When is the first frost in Flagstaff, AZ?

The median first fall frost near 86004 is September 19, giving a median frost-free growing season of 94 days.

When should I plant tomatoes in 86004?

Start tomato seeds indoors around Apr 21 – May 5 and set transplants outside around Jun 23 – Jul 7, one to three weeks after the median last frost.

How much rain and snow does 86004 get?

About 17 inches of precipitation a year and 49 inches of snowfall (NOAA 1991–2020 normals, Sunset Crater Nm station).

How hot do summers get in Flagstaff, AZ?

The average high peaks at 84 °F in July, with about 13 days a year at 90 °F or more.

What kind of soil does 86004 have?

The USDA soil survey maps Wukoki at the center of ZIP 86004: very gravelly loam, somewhat excessively drained, pH about 7.6 (slightly alkaline).

Did spring come early in Flagstaff, AZ in 2026?

Spring leaf-out near 86004 came on Feb 23 in 2026, 19 days earlier than the 1991–2020 average (Mar 14), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Flagstaff, AZ?

Intermediate onions: the longest day near 86004 is 14 h 33 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 86004 change?

Yes. The 2012 USDA map put 86004 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.