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

Planting zone for 82630 — Arminto, WY

ZIP code 82630 (Arminto, Natrona County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 30 and the first fall frost September 22.

Where ZIP 82630 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.

Zone5a−20 to −15 °F

Coldest night−28.9 to −26.1 °C

Last frostMay 30

First frostSep 22

2012 zone4a

Was 4a on the 2012 map — a full zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Arminto, WY…

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 Arminto, WY

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 30median — 50% chance of a later frost

Safe for tender plantsJune 13only 10% chance of frost after

First fall frostSeptember 22median — 10% chance by Sep 8

Growing season115 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 12 and returns around October 1.

From the NOAA station Powder Rvr (School), WY — 26 miles away, elevation 5,722 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 82630

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 18 – May 2

SpinachSow outdoors · Apr 18 – May 9

Broccoli, cabbageStart indoors · Mar 21 – Apr 4

Broccoli, cabbageTransplant · May 9 – May 23

Onion setsPlant outdoors · May 2 – May 16

PotatoesPlant outdoors · May 9 – May 23

LettuceSow outdoors · May 2 – May 16

Carrots, beetsSow outdoors · May 9 – May 23

TomatoesStart indoors · Apr 4 – Apr 18

TomatoesTransplant · Jun 6 – Jun 20

Peppers, eggplantStart indoors · Mar 21 – Apr 4

Peppers, eggplantTransplant · Jun 13 – Jun 27

BeansSow outdoors · Jun 6 – Jun 20

Sweet cornSow outdoors · Jun 6 – Jun 20

Cucumbers, squashSow outdoors · Jun 6 – Jun 20

Fall lettuce, spinachSow outdoors · Jul 28 – Aug 11

GarlicPlant cloves · Sep 8 – Oct 13

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 30) and first fall frost (Sep 22) 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 82630 came on Apr 26 — 15 days earlier than the 1991–2020 average (May 11).

average
May 112026
Apr 26

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 5a in Wyoming

542 plants native to the lower 48 states, recorded in Wyoming, and rated by the USDA to survive −20 °F or colder — the bottom of zone 5a. 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 Arminto, WY.

Soil in Arminto, WY

The soil mapped at the center of ZIP 82630 is Nathrop — very stony loam, well drained.

TextureVery stony loama good balance for most vegetables

pH7.0neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2.5%moderate

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Nathrop-Starley complex, 8 to 35 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 82630; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Arminto, WY

Summer high87 °Faverage high, July

Winter low10 °Faverage low, December

Hot days31days a year at 90 °F or more

Freezing nights200nights a year at 32 °F or less

Growing degree days1,924base 50 °F — the season’s usable heat

Longest day15 h 24 mindaylight on June 21

Shortest day8 h 58 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation21.1 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Powder Rvr (School), WY (26 mi away); precipitation: Grave Springs, WY (11 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.

Powder River, WY · 25 mi

Ten Sleep, WY · 40 mi

Wyoming planting zones →

Questions about 82630

What planting zone is ZIP code 82630?

ZIP code 82630 (Arminto, WY) is in USDA hardiness zone 5a on the 2023 map: the coldest night of an average winter reaches −20 to −15 °F (−28.9 to −26.1 °C).

When is the last frost in Arminto, WY?

The median last spring frost (32 °F) near 82630 is May 30; after June 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Powder Rvr (School) station.

When is the first frost in Arminto, WY?

The median first fall frost near 82630 is September 22, giving a median frost-free growing season of 115 days.

When should I plant tomatoes in 82630?

Start tomato seeds indoors around Apr 4 – Apr 18 and set transplants outside around Jun 6 – Jun 20, one to three weeks after the median last frost.

How much rain and snow does 82630 get?

About 21.1 inches of precipitation a year (NOAA 1991–2020 normals, Grave Springs station).

How hot do summers get in Arminto, WY?

The average high peaks at 87 °F in July, with about 31 days a year at 90 °F or more.

What kind of soil does 82630 have?

The USDA soil survey maps Nathrop at the center of ZIP 82630: very stony loam, well drained, pH about 7.0 (neutral).

Did spring come early in Arminto, WY in 2026?

Spring leaf-out near 82630 came on Apr 26 in 2026, 15 days earlier than the 1991–2020 average (May 11), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Arminto, WY?

Long-day onions: the longest day near 82630 is 15 h 24 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 82630 change?

Yes. The 2012 USDA map put 82630 in zone 4a; the 2023 map puts it in zone 5a. The newer map uses 1991–2020 data and more weather stations.