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

Planting zone for 85631 — San Manuel, AZ

ZIP code 85631 (San Manuel, Pinal County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is February 4 and the first fall frost December 8.

Where ZIP 85631 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.

Zone9a20 to 25 °F
Coldest night−6.7 to −3.9 °C
Last frostFeb 4
First frostDec 8
2012 zone9a

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 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for San Manuel, 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 San Manuel, AZ

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 4median — 50% chance of a later frost
Safe for tender plantsMarch 2only 10% chance of frost after
First fall frostDecember 8median — 10% chance by Nov 20
Growing season306 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 10 and returns around December 22.

From the NOAA station San Manuel, AZ — 4 miles away, elevation 3,419 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 85631

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Dec 24 – Jan 7
SpinachSow outdoors · Dec 24 – Jan 14
Broccoli, cabbageStart indoors · Nov 26 – Dec 10
Broccoli, cabbageTransplant · Jan 14 – Jan 28
Onion setsPlant outdoors · Jan 7 – Jan 21
PotatoesPlant outdoors · Jan 14 – Jan 28
LettuceSow outdoors · Jan 7 – Jan 21
Carrots, beetsSow outdoors · Jan 14 – Jan 28
TomatoesStart indoors · Dec 10 – Dec 24
TomatoesTransplant · Feb 11 – Feb 25
Peppers, eggplantStart indoors · Nov 26 – Dec 10
Peppers, eggplantTransplant · Feb 18 – Mar 4
BeansSow outdoors · Feb 11 – Feb 25
Sweet cornSow outdoors · Feb 11 – Feb 25
Cucumbers, squashSow outdoors · Feb 11 – Feb 25
Fall lettuce, spinachSow outdoors · Oct 13 – Oct 27
GarlicPlant cloves · Nov 24 – Dec 29
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 4) and first fall frost (Dec 8) 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 85631 came on Jan 27 — about the same time as the 1991–2020 average (Jan 29).

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 9a in Arizona

492 plants native to the lower 48 states, recorded in Arizona, and rated by the USDA to survive 20 °F or colder — the bottom of zone 9a. Each links to its USDA PLANTS profile.

Trees 26

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 109

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 197

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 151

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 San Manuel, AZ.

Soil in San Manuel, AZ

The soil mapped at the center of ZIP 85631 is Nahda — very gravelly clay loam, well drained.

TextureVery gravelly 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 matter0.75%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Nahda-Delnorte complex, 1 to 10 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 85631; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in San Manuel, AZ

Summer high97 °Faverage high, June
Winter low38 °Faverage low, January
Hot days116days a year at 90 °F or more
Freezing nights14nights a year at 32 °F or less
Growing degree days6,380base 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 growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb
Precipitation12.6 inper year, rain and melted snow
Snowfall1 inper year

Average high and low, by month

30°40°50°60°70°80°90°100°110°32 °FJanuary: average high 60 °F, low 38 °F 60°38° JanFebruary: average high 64 °F, low 41 °F 64°41° FebMarch: average high 71 °F, low 46 °F 71°46° MarApril: average high 79 °F, low 51 °F 79°51° AprMay: average high 88 °F, low 59 °F 88°59° MayJune: average high 97 °F, low 69 °F 97°69° JunJuly: average high 97 °F, low 72 °F 97°72° JulAugust: average high 94 °F, low 71 °F 94°71° AugSeptember: average high 90 °F, low 66 °F 90°66° SepOctober: average high 80 °F, low 57 °F 80°57° OctNovember: average high 69 °F, low 45 °F 69°45° NovDecember: average high 59 °F, low 38 °F 59°38° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″January: 1.12 in precipitation, 0.3 in snowfall 1.1 JanFebruary: 1.14 in precipitation, 0.1 in snowfall 1.1 FebMarch: 0.65 in precipitation, 0.1 in snowfall 0.7 MarApril: 0.36 in precipitation, 0.1 in snowfall 0.4 AprMay: 0.31 in precipitation 0.3 MayJune: 0.34 in precipitation 0.3 JunJuly: 2.38 in precipitation 2.4 JulAugust: 2.78 in precipitation 2.8 AugSeptember: 1.29 in precipitation 1.3 SepOctober: 0.59 in precipitation 0.6 OctNovember: 0.62 in precipitation 0.6 NovDecember: 1.03 in precipitation, 0.1 in snowfall 1.0 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: San Manuel, AZ (4 mi away); precipitation: San Manuel, AZ (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

856239a
Oracle, AZ · 14 mi
856189a
Mammoth, AZ · 16 mi
856198b
Mount Lemmon, AZ · 16 mi
857389a
Catalina, AZ · 22 mi
857499a
Tucson, AZ · 23 mi
857379a
Tucson, AZ · 25 mi
857509a
Tucson, AZ · 26 mi
857559a
Tucson, AZ · 26 mi

Arizona planting zones →

Questions about 85631

What planting zone is ZIP code 85631?

ZIP code 85631 (San Manuel, AZ) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in San Manuel, AZ?

The median last spring frost (32 °F) near 85631 is February 4; after March 2 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, San Manuel station.

When is the first frost in San Manuel, AZ?

The median first fall frost near 85631 is December 8, giving a median frost-free growing season of 306 days.

When should I plant tomatoes in 85631?

Start tomato seeds indoors around Dec 10 – Dec 24 and set transplants outside around Feb 11 – Feb 25, one to three weeks after the median last frost.

How much rain and snow does 85631 get?

About 12.6 inches of precipitation a year and 1 inches of snowfall (NOAA 1991–2020 normals, San Manuel station).

How hot do summers get in San Manuel, AZ?

The average high peaks at 97 °F in June, with about 116 days a year at 90 °F or more.

What kind of soil does 85631 have?

The USDA soil survey maps Nahda at the center of ZIP 85631: very gravelly clay loam, well drained, pH about 7.9 (alkaline).

Did spring come early in San Manuel, AZ in 2026?

Spring leaf-out near 85631 came on Jan 27 in 2026, about the same as the 1991–2020 average (Jan 29), according to the USA National Phenology Network Spring Index.

What kind of onions grow in San Manuel, AZ?

Short-day onions: the longest day near 85631 is 14 h 18 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.