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

Planting zone for 82711 — Alva, WY

ZIP code 82711 (Alva, Crook County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 17 and the first fall frost September 23.

Where ZIP 82711 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 17
First frostSep 23
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 Alva, 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 Alva, WY

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 17median — 50% chance of a later frost
Safe for tender plantsMay 30only 10% chance of frost after
First fall frostSeptember 23median — 10% chance by Sep 8
Growing season128 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 6 and returns around October 3.

From the NOAA station Hulett, WY — 6 miles away, elevation 3,757 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 82711

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 5 – Apr 19
SpinachSow outdoors · Apr 5 – Apr 26
Broccoli, cabbageStart indoors · Mar 8 – Mar 22
Broccoli, cabbageTransplant · Apr 26 – May 10
Onion setsPlant outdoors · Apr 19 – May 3
PotatoesPlant outdoors · Apr 26 – May 10
LettuceSow outdoors · Apr 19 – May 3
Carrots, beetsSow outdoors · Apr 26 – May 10
TomatoesStart indoors · Mar 22 – Apr 5
TomatoesTransplant · May 24 – Jun 7
Peppers, eggplantStart indoors · Mar 8 – Mar 22
Peppers, eggplantTransplant · May 31 – Jun 14
BeansSow outdoors · May 24 – Jun 7
Sweet cornSow outdoors · May 24 – Jun 7
Cucumbers, squashSow outdoors · May 24 – Jun 7
Fall lettuce, spinachSow outdoors · Jul 29 – Aug 12
GarlicPlant cloves · Sep 9 – Oct 14
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 17) and first fall frost (Sep 23) 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 82711 came on Mar 22 — 24 days earlier than the 1991–2020 average (Apr 15).

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.

Trees 22

American elm120 ft · blooms early spring · medium shade tolerance · to −46 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fblue spruce100 ft · blooms late spring · medium shade tolerance · to −38 °Fboxelder60 ft · blooms early spring · low shade tolerance · to −46 °FDouglas-fir200 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 98

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °Falderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °F

Wildflowers & perennials 249

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 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °F

Grasses 161

Alaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °Falkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °FAlpine Meadow-Foxtail0.5 ft · blooms mid spring · medium shade tolerance · to −33 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Fanalogue sedge1.5 ft · blooms late spring · medium shade tolerance · to −38 °F

Vines 3

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fwestern 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 Alva, WY.

Soil in Alva, WY

The soil mapped at the center of ZIP 82711 is Samsil — clay, well drained.

TextureClayholds water and nutrients; slow to drain and warm up
pH7.7slightly alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter0.9%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Samsil-Cromack complex, 10 to 30 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 82711; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Alva, WY

Summer high86 °Faverage high, July
Winter low11 °Faverage low, January
Hot days29days a year at 90 °F or more
Freezing nights188nights a year at 32 °F or less
Growing degree days2,189base 50 °F — the season’s usable heat
Longest day15 h 35 mindaylight on June 21
Shortest day8 h 48 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation18.4 inper year, rain and melted snow
Snowfall49 inper year

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 34 °F, low 11 °F 34°11° JanFebruary: average high 37 °F, low 13 °F 37°13° FebMarch: average high 47 °F, low 22 °F 47°22° MarApril: average high 56 °F, low 30 °F 56°30° AprMay: average high 66 °F, low 40 °F 66°40° MayJune: average high 77 °F, low 49 °F 77°49° JunJuly: average high 86 °F, low 55 °F 86°55° JulAugust: average high 85 °F, low 53 °F 85°53° AugSeptember: average high 75 °F, low 43 °F 75°43° SepOctober: average high 59 °F, low 32 °F 59°32° OctNovember: average high 45 °F, low 21 °F 45°21° NovDecember: average high 35 °F, low 12 °F 35°12° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″January: 0.59 in precipitation, 7.6 in snowfall 0.6❄8 JanFebruary: 0.63 in precipitation, 7.9 in snowfall 0.6❄8 FebMarch: 1.09 in precipitation, 9.7 in snowfall 1.1❄10 MarApril: 2.09 in precipitation, 6.2 in snowfall 2.1❄6 AprMay: 3.06 in precipitation, 1 in snowfall 3.1❄1 MayJune: 3.00 in precipitation 3.0 JunJuly: 2.07 in precipitation 2.1 JulAugust: 1.27 in precipitation 1.3 AugSeptember: 1.18 in precipitation, 0.1 in snowfall 1.2 SepOctober: 2.00 in precipitation, 3.3 in snowfall 2.0❄3 OctNovember: 0.83 in precipitation, 6.8 in snowfall 0.8❄7 NovDecember: 0.54 in precipitation, 6.6 in snowfall 0.5❄7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Hulett, WY (6 mi away); precipitation: Hulett, WY (6 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.

827105a
Aladdin, WY · 9 mi
827204b
Hulett, WY · 11 mi
827144b
Devils Tower, WY · 15 mi
827125a
Beulah, WY · 22 mi
827294b
Sundance, WY · 24 mi
827214b
Moorcroft, WY · 27 mi
593114b
Alzada, MT · 31 mi
577835b
Spearfish, SD · 33 mi

Wyoming planting zones →

Questions about 82711

What planting zone is ZIP code 82711?

ZIP code 82711 (Alva, 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 Alva, WY?

The median last spring frost (32 °F) near 82711 is May 17; after May 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Hulett station.

When is the first frost in Alva, WY?

The median first fall frost near 82711 is September 23, giving a median frost-free growing season of 128 days.

When should I plant tomatoes in 82711?

Start tomato seeds indoors around Mar 22 – Apr 5 and set transplants outside around May 24 – Jun 7, one to three weeks after the median last frost.

How much rain and snow does 82711 get?

About 18.4 inches of precipitation a year and 49 inches of snowfall (NOAA 1991–2020 normals, Hulett station).

How hot do summers get in Alva, WY?

The average high peaks at 86 °F in July, with about 29 days a year at 90 °F or more.

What kind of soil does 82711 have?

The USDA soil survey maps Samsil at the center of ZIP 82711: clay, well drained, pH about 7.7 (slightly alkaline).

Did spring come early in Alva, WY in 2026?

Spring leaf-out near 82711 came on Mar 22 in 2026, 24 days earlier than the 1991–2020 average (Apr 15), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Alva, WY?

Long-day onions: the longest day near 82711 is 15 h 35 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 82711 change?

Yes. The 2012 USDA map put 82711 in zone 4a; the 2023 map puts it in zone 5a. The newer map uses 1991–2020 data and more weather stations.