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

Planting zone for 85619 — Mount Lemmon, AZ

ZIP code 85619 (Mount Lemmon, Pima 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 19.

Where ZIP 85619 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 19
2012 zone7a

Was 7a on the 2012 map — 1.5 zones warmer now. 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 Mount Lemmon, 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 Mount Lemmon, 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 21only 10% chance of frost after
First fall frostNovember 19median — 10% chance by Oct 30
Growing season229 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 12 and returns around November 30.

From the NOAA station Mt Lemmon Willow Canyon, AZ — 2 miles away, elevation 7,028 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 85619

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 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 (Apr 1) 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 85619 came on Feb 8 — about the same time as the 1991–2020 average (Feb 7).

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.

Trees 25

Arizona cypress50 ft · blooms spring · low shade tolerance · to −23 °FArizona madrone30 ft · blooms late spring · high shade tolerance · to −4 °FArizona sycamore80 ft · blooms early spring · high shade tolerance · to −8 °FArizona walnut50 ft · blooms late spring · high shade tolerance · to −33 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fblue spruce100 ft · blooms late spring · medium shade tolerance · to −38 °F

Shrubs 105

alderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °FAmerican tarwort3 ft · blooms late spring · high shade tolerance · to −23 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °FApache plume6 ft · blooms late spring · high shade tolerance · to −23 °Fbig sagebrush4 ft · blooms mid summer · high shade tolerance · to −43 °F

Wildflowers & perennials 196

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °FAmerican century plant6 ft · blooms indeterminate · high shade tolerance · to 12 °F

Grasses 147

alkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Fanalogue sedge1.5 ft · blooms late spring · medium shade tolerance · to −38 °FArizona cottontop4 ft · blooms late summer · high shade tolerance · to −13 °FArizona fescue2 ft · blooms late spring · high shade tolerance · to −23 °F

Vines 1

western white clematis1 ft · blooms mid summer · medium shade tolerance · to −38 °F

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 Mount Lemmon, AZ.

Soil in Mount Lemmon, AZ

The soil mapped at the center of ZIP 85619 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, Typic Haplustolls, and Vitrandic Haplustolls; cool 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 85619; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Mount Lemmon, AZ

Summer high80 °Faverage high, June
Winter low33 °Faverage low, February
Hot days5days a year at 90 °F or more
Freezing nights53nights a year at 32 °F or less
Growing degree days3,282base 50 °F — the season’s usable heat
Longest day14 h 17 mindaylight on June 21
Shortest day10 h 01 mindaylight on December 21
Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb
Precipitation12.9 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°32 °FJanuary: average high 50 °F, low 34 °F 50°34° JanFebruary: average high 50 °F, low 33 °F 50°33° FebMarch: average high 55 °F, low 37 °F 55°37° MarApril: average high 62 °F, low 43 °F 62°43° AprMay: average high 71 °F, low 51 °F 71°51° MayJune: average high 80 °F, low 60 °F 80°60° JunJuly: average high 80 °F, low 64 °F 80°64° JulAugust: average high 79 °F, low 62 °F 79°62° AugSeptember: average high 75 °F, low 59 °F 75°59° SepOctober: average high 68 °F, low 49 °F 68°49° OctNovember: average high 59 °F, low 40 °F 59°40° NovDecember: average high 49 °F, low 33 °F 49°33° Dec

Precipitation by month inches

0″1″2″3″January: 1.09 in precipitation 1.1 JanFebruary: 1.15 in precipitation 1.1 FebMarch: 0.74 in precipitation 0.7 MarApril: 0.30 in precipitation 0.3 AprMay: 0.20 in precipitation 0.2 MayJune: 0.43 in precipitation 0.4 JunJuly: 2.36 in precipitation 2.4 JulAugust: 2.52 in precipitation 2.5 AugSeptember: 1.42 in precipitation 1.4 SepOctober: 0.82 in precipitation 0.8 OctNovember: 0.64 in precipitation 0.6 NovDecember: 1.23 in precipitation 1.2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Mt Lemmon Willow Canyon, AZ (2 mi away); precipitation: Tucson 11.8 Ene, 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.

857499a
Tucson, AZ · 8 mi
857509a
Tucson, AZ · 9 mi
857159b
Tucson, AZ · 12 mi
857189a
Tucson, AZ · 12 mi
857489a
Tucson, AZ · 12 mi
857379a
Tucson, AZ · 12 mi
857389a
Catalina, AZ · 13 mi
857129b
Tucson, AZ · 13 mi

Arizona planting zones →

Questions about 85619

What planting zone is ZIP code 85619?

ZIP code 85619 (Mount Lemmon, 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 Mount Lemmon, AZ?

The median last spring frost (32 °F) near 85619 is April 1; after April 21 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Mt Lemmon Willow Canyon station.

When is the first frost in Mount Lemmon, AZ?

The median first fall frost near 85619 is November 19, giving a median frost-free growing season of 229 days.

When should I plant tomatoes in 85619?

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 85619 get?

About 12.9 inches of precipitation a year (NOAA 1991–2020 normals, Tucson 11.8 Ene station).

How hot do summers get in Mount Lemmon, AZ?

The average high peaks at 80 °F in June, with about 5 days a year at 90 °F or more.

What kind of soil does 85619 have?

The USDA soil survey maps Lithic Argiustolls at the center of ZIP 85619: extremely cobbly loam, well drained, pH about 7.2 (neutral).

Did spring come early in Mount Lemmon, AZ in 2026?

Spring leaf-out near 85619 came on Feb 8 in 2026, about the same as the 1991–2020 average (Feb 7), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Mount Lemmon, AZ?

Short-day onions: the longest day near 85619 is 14 h 17 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.

Did the zone for 85619 change?

Yes. The 2012 USDA map put 85619 in zone 7a; the 2023 map puts it in zone 8b. The newer map uses 1991–2020 data and more weather stations.