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

Planting zone for 82639 — Kaycee, WY

ZIP code 82639 (Kaycee, Johnson County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 18 and the first fall frost September 25.

Where ZIP 82639 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 18
First frostSep 25
2012 zone4b

Was 4b 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 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Kaycee, 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 Kaycee, WY

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 18median — 50% chance of a later frost
Safe for tender plantsMay 31only 10% chance of frost after
First fall frostSeptember 25median — 10% chance by Sep 11
Growing season129 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 6 and returns around October 5.

From the NOAA station Kaycee, WY — 3 miles away, elevation 4,659 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 82639

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 6 – Apr 20
SpinachSow outdoors · Apr 6 – Apr 27
Broccoli, cabbageStart indoors · Mar 9 – Mar 23
Broccoli, cabbageTransplant · Apr 27 – May 11
Onion setsPlant outdoors · Apr 20 – May 4
PotatoesPlant outdoors · Apr 27 – May 11
LettuceSow outdoors · Apr 20 – May 4
Carrots, beetsSow outdoors · Apr 27 – May 11
TomatoesStart indoors · Mar 23 – Apr 6
TomatoesTransplant · May 25 – Jun 8
Peppers, eggplantStart indoors · Mar 9 – Mar 23
Peppers, eggplantTransplant · Jun 1 – Jun 15
BeansSow outdoors · May 25 – Jun 8
Sweet cornSow outdoors · May 25 – Jun 8
Cucumbers, squashSow outdoors · May 25 – Jun 8
Fall lettuce, spinachSow outdoors · Jul 31 – Aug 14
GarlicPlant cloves · Sep 11 – Oct 16
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 18) and first fall frost (Sep 25) 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 82639 came on Mar 12 — 29 days earlier than the 1991–2020 average (Apr 10).

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 Kaycee, WY.

Soil in Kaycee, WY

The soil mapped at the center of ZIP 82639 is Samday — clay loam, well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up
pH7.8slightly alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Samday-Shingle-Badland complex, 10 to 45 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 82639; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Kaycee, WY

Summer high88 °Faverage high, July
Winter low10 °Faverage low, January
Hot days38days a year at 90 °F or more
Freezing nights192nights a year at 32 °F or less
Growing degree days2,204base 50 °F — the season’s usable heat
Longest day15 h 27 mindaylight on June 21
Shortest day8 h 55 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation11.9 inper year, rain and melted snow
Snowfall41 inper year; 58 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 37 °F, low 10 °F 37°10° JanFebruary: average high 39 °F, low 13 °F 39°13° FebMarch: average high 49 °F, low 21 °F 49°21° MarApril: average high 56 °F, low 29 °F 56°29° AprMay: average high 66 °F, low 39 °F 66°39° MayJune: average high 78 °F, low 48 °F 78°48° JunJuly: average high 88 °F, low 55 °F 88°55° JulAugust: average high 86 °F, low 52 °F 86°52° AugSeptember: average high 76 °F, low 42 °F 76°42° SepOctober: average high 60 °F, low 30 °F 60°30° OctNovember: average high 47 °F, low 19 °F 47°19° NovDecember: average high 37 °F, low 10 °F 37°10° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″January: 0.26 in precipitation, 5.6 in snowfall 0.3❄6 JanFebruary: 0.41 in precipitation, 8.9 in snowfall 0.4❄9 FebMarch: 0.67 in precipitation, 6.5 in snowfall 0.7❄7 MarApril: 1.50 in precipitation, 3.8 in snowfall 1.5❄4 AprMay: 2.75 in precipitation, 0.6 in snowfall 2.8❄1 MayJune: 1.63 in precipitation, 0.1 in snowfall 1.6 JunJuly: 1.16 in precipitation 1.2 JulAugust: 0.70 in precipitation 0.7 AugSeptember: 1.03 in precipitation, 0.3 in snowfall 1.0 SepOctober: 1.04 in precipitation, 2.3 in snowfall 1.0❄2 OctNovember: 0.46 in precipitation, 5.8 in snowfall 0.5❄6 NovDecember: 0.34 in precipitation, 6.8 in snowfall 0.3❄7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Kaycee, WY (3 mi away); precipitation: Kaycee, WY (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5a.

826435a
Midwest, WY · 30 mi
826405a
Linch, WY · 31 mi
826355a
Edgerton, WY · 32 mi
824425a
Ten Sleep, WY · 34 mi
828345a
Buffalo, WY · 36 mi
826305a
Arminto, WY · 42 mi
826485a
Powder River, WY · 46 mi
826015a
Casper, WY · 49 mi

Wyoming planting zones →

Questions about 82639

What planting zone is ZIP code 82639?

ZIP code 82639 (Kaycee, 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 Kaycee, WY?

The median last spring frost (32 °F) near 82639 is May 18; after May 31 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Kaycee station.

When is the first frost in Kaycee, WY?

The median first fall frost near 82639 is September 25, giving a median frost-free growing season of 129 days.

When should I plant tomatoes in 82639?

Start tomato seeds indoors around Mar 23 – Apr 6 and set transplants outside around May 25 – Jun 8, one to three weeks after the median last frost.

How much rain and snow does 82639 get?

About 11.9 inches of precipitation a year and 41 inches of snowfall (NOAA 1991–2020 normals, Kaycee station).

How hot do summers get in Kaycee, WY?

The average high peaks at 88 °F in July, with about 38 days a year at 90 °F or more.

What kind of soil does 82639 have?

The USDA soil survey maps Samday at the center of ZIP 82639: clay loam, well drained, pH about 7.8 (slightly alkaline).

Did spring come early in Kaycee, WY in 2026?

Spring leaf-out near 82639 came on Mar 12 in 2026, 29 days earlier than the 1991–2020 average (Apr 10), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Kaycee, WY?

Long-day onions: the longest day near 82639 is 15 h 27 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 82639 change?

Yes. The 2012 USDA map put 82639 in zone 4b; the 2023 map puts it in zone 5a. The newer map uses 1991–2020 data and more weather stations.