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

Planting zone for 82938 — Mc Kinnon, WY

ZIP code 82938 (Mc Kinnon, Sweetwater County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 22 and the first fall frost September 29.

Where ZIP 82938 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.

Zone5b−15 to −10 °F
Coldest night−26.1 to −23.3 °C
Last frostMay 22
First frostSep 29
2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Mc Kinnon, 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 Mc Kinnon, WY

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 22median — 50% chance of a later frost
Safe for tender plantsJune 11only 10% chance of frost after
First fall frostSeptember 29median — 10% chance by Sep 15
Growing season128 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 5 and returns around October 11.

From the NOAA station Manila, UT — 11 miles away, elevation 6,395 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 82938

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 10 – Apr 24
SpinachSow outdoors · Apr 10 – May 1
Broccoli, cabbageStart indoors · Mar 13 – Mar 27
Broccoli, cabbageTransplant · May 1 – May 15
Onion setsPlant outdoors · Apr 24 – May 8
PotatoesPlant outdoors · May 1 – May 15
LettuceSow outdoors · Apr 24 – May 8
Carrots, beetsSow outdoors · May 1 – May 15
TomatoesStart indoors · Mar 27 – Apr 10
TomatoesTransplant · May 29 – Jun 12
Peppers, eggplantStart indoors · Mar 13 – Mar 27
Peppers, eggplantTransplant · Jun 5 – Jun 19
BeansSow outdoors · May 29 – Jun 12
Sweet cornSow outdoors · May 29 – Jun 12
Cucumbers, squashSow outdoors · May 29 – Jun 12
Fall lettuce, spinachSow outdoors · Aug 4 – Aug 18
GarlicPlant cloves · Sep 15 – Oct 20
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 22) and first fall frost (Sep 29) 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 82938 came on Mar 24 — 29 days earlier than the 1991–2020 average (Apr 22).

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 5b in Wyoming

549 plants native to the lower 48 states, recorded in Wyoming, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. 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 99

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 254

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 162

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 Mc Kinnon, WY.

Soil in Mc Kinnon, WY

The center of ZIP 82938 is mapped as No Digital Data Available: built-over ground without natural soil data. Garden soil here is usually imported or disturbed — test before you plant.

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 82938; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Mc Kinnon, WY

Summer high83 °Faverage high, July
Winter low12 °Faverage low, January
Hot days6days a year at 90 °F or more
Freezing nights190nights a year at 32 °F or less
Growing degree days1,833base 50 °F — the season’s usable heat
Longest day15 h 08 mindaylight on June 21
Shortest day9 h 13 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation11.5 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 36 °F, low 12 °F 36°12° JanFebruary: average high 39 °F, low 15 °F 39°15° FebMarch: average high 49 °F, low 24 °F 49°24° MarApril: average high 56 °F, low 30 °F 56°30° AprMay: average high 65 °F, low 39 °F 65°39° MayJune: average high 76 °F, low 46 °F 76°46° JunJuly: average high 83 °F, low 54 °F 83°54° JulAugust: average high 81 °F, low 51 °F 81°51° AugSeptember: average high 72 °F, low 43 °F 72°43° SepOctober: average high 60 °F, low 32 °F 60°32° OctNovember: average high 45 °F, low 21 °F 45°21° NovDecember: average high 34 °F, low 14 °F 34°14° Dec

Precipitation by month inches

0″1″2″January: 0.51 in precipitation 0.5 JanFebruary: 0.55 in precipitation 0.6 FebMarch: 0.55 in precipitation 0.6 MarApril: 1.02 in precipitation 1.0 AprMay: 1.56 in precipitation 1.6 MayJune: 1.19 in precipitation 1.2 JunJuly: 1.08 in precipitation 1.1 JulAugust: 1.32 in precipitation 1.3 AugSeptember: 1.04 in precipitation 1.0 SepOctober: 1.53 in precipitation 1.5 OctNovember: 0.53 in precipitation 0.5 NovDecember: 0.58 in precipitation 0.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Manila, UT (11 mi away); precipitation: Manila, UT (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

840465b
Manila, UT · 11 mi
829365b
Lonetree, WY · 15 mi
829395b
Mountain View, WY · 25 mi
829375a
Lyman, WY · 26 mi
829445a
Robertson, WY · 31 mi
829295a
Little America, WY · 31 mi
829335b
Fort Bridger, WY · 33 mi
840856a
Whiterocks, UT · 36 mi

Wyoming planting zones →

Questions about 82938

What planting zone is ZIP code 82938?

ZIP code 82938 (Mc Kinnon, WY) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Mc Kinnon, WY?

The median last spring frost (32 °F) near 82938 is May 22; after June 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Manila station.

When is the first frost in Mc Kinnon, WY?

The median first fall frost near 82938 is September 29, giving a median frost-free growing season of 128 days.

When should I plant tomatoes in 82938?

Start tomato seeds indoors around Mar 27 – Apr 10 and set transplants outside around May 29 – Jun 12, one to three weeks after the median last frost.

How much rain and snow does 82938 get?

About 11.5 inches of precipitation a year (NOAA 1991–2020 normals, Manila station).

How hot do summers get in Mc Kinnon, WY?

The average high peaks at 83 °F in July, with about 6 days a year at 90 °F or more.

Did spring come early in Mc Kinnon, WY in 2026?

Spring leaf-out near 82938 came on Mar 24 in 2026, 29 days earlier than the 1991–2020 average (Apr 22), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Mc Kinnon, WY?

Long-day onions: the longest day near 82938 is 15 h 08 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).