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

Planting zone for 82412 — Byron, WY

ZIP code 82412 (Byron, Big Horn County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 6 and the first fall frost October 1.

Where ZIP 82412 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 6
First frostOct 1
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 Byron, 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 Byron, WY

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 6median — 50% chance of a later frost
Safe for tender plantsMay 20only 10% chance of frost after
First fall frostOctober 1median — 10% chance by Sep 19
Growing season148 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 27 and returns around October 12.

From the NOAA station Deaver, WY — 7 miles away, elevation 4,105 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 82412

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 25 – Apr 8
SpinachSow outdoors · Mar 25 – Apr 15
Broccoli, cabbageStart indoors · Feb 25 – Mar 11
Broccoli, cabbageTransplant · Apr 15 – Apr 29
Onion setsPlant outdoors · Apr 8 – Apr 22
PotatoesPlant outdoors · Apr 15 – Apr 29
LettuceSow outdoors · Apr 8 – Apr 22
Carrots, beetsSow outdoors · Apr 15 – Apr 29
TomatoesStart indoors · Mar 11 – Mar 25
TomatoesTransplant · May 13 – May 27
Peppers, eggplantStart indoors · Feb 25 – Mar 11
Peppers, eggplantTransplant · May 20 – Jun 3
BeansSow outdoors · May 13 – May 27
Sweet cornSow outdoors · May 13 – May 27
Cucumbers, squashSow outdoors · May 13 – May 27
Fall lettuce, spinachSow outdoors · Aug 6 – Aug 20
GarlicPlant cloves · Sep 17 – Oct 22
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 6) and first fall frost (Oct 1) 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 82412 came on Mar 22 — 17 days earlier than the 1991–2020 average (Apr 8).

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 Byron, WY.

Soil in Byron, WY

The soil mapped at the center of ZIP 82412 is Greybull — loam, well drained.

TextureLoama good balance for most vegetables
pH8.4alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter0.75%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Greybull-Persayo complex, 0 to 30 percent slopes -- Draft.

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 82412; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Byron, WY

Summer high90 °Faverage high, July
Winter low7 °Faverage low, January
Hot days41days a year at 90 °F or more
Freezing nights187nights a year at 32 °F or less
Growing degree days2,542base 50 °F — the season’s usable heat
Longest day15 h 35 mindaylight on June 21
Shortest day8 h 47 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation9.6 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 31 °F, low 7 °F 31°7° JanFebruary: average high 37 °F, low 12 °F 37°12° FebMarch: average high 51 °F, low 23 °F 51°23° MarApril: average high 60 °F, low 32 °F 60°32° AprMay: average high 70 °F, low 43 °F 70°43° MayJune: average high 80 °F, low 51 °F 80°51° JunJuly: average high 90 °F, low 57 °F 90°57° JulAugust: average high 88 °F, low 55 °F 88°55° AugSeptember: average high 77 °F, low 44 °F 77°44° SepOctober: average high 61 °F, low 33 °F 61°33° OctNovember: average high 45 °F, low 20 °F 45°20° NovDecember: average high 33 °F, low 9 °F 33°9° Dec

Precipitation by month inches

0″1″2″January: 0.56 in precipitation 0.6 JanFebruary: 0.48 in precipitation 0.5 FebMarch: 0.32 in precipitation 0.3 MarApril: 0.99 in precipitation 1.0 AprMay: 1.45 in precipitation 1.4 MayJune: 1.56 in precipitation 1.6 JunJuly: 0.83 in precipitation 0.8 JulAugust: 0.48 in precipitation 0.5 AugSeptember: 1.27 in precipitation 1.3 SepOctober: 0.80 in precipitation 0.8 OctNovember: 0.58 in precipitation 0.6 NovDecember: 0.32 in precipitation 0.3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Deaver, WY (7 mi away); precipitation: Lovell 2.4 Ssw, WY (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5a.

824215a
Deaver, WY · 7 mi
824205a
Cowley, WY · 10 mi
824235a
Frannie, WY · 14 mi
824405a
Ralston, WY · 16 mi
824315a
Lovell, WY · 20 mi
824225a
Emblem, WY · 22 mi
824115a
Burlington, WY · 24 mi
824355a
Powell, WY · 25 mi

Wyoming planting zones →

Questions about 82412

What planting zone is ZIP code 82412?

ZIP code 82412 (Byron, 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 Byron, WY?

The median last spring frost (32 °F) near 82412 is May 6; after May 20 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Deaver station.

When is the first frost in Byron, WY?

The median first fall frost near 82412 is October 1, giving a median frost-free growing season of 148 days.

When should I plant tomatoes in 82412?

Start tomato seeds indoors around Mar 11 – Mar 25 and set transplants outside around May 13 – May 27, one to three weeks after the median last frost.

How much rain and snow does 82412 get?

About 9.6 inches of precipitation a year (NOAA 1991–2020 normals, Lovell 2.4 Ssw station).

How hot do summers get in Byron, WY?

The average high peaks at 90 °F in July, with about 41 days a year at 90 °F or more.

What kind of soil does 82412 have?

The USDA soil survey maps Greybull at the center of ZIP 82412: loam, well drained, pH about 8.4 (alkaline).

Did spring come early in Byron, WY in 2026?

Spring leaf-out near 82412 came on Mar 22 in 2026, 17 days earlier than the 1991–2020 average (Apr 8), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Byron, WY?

Long-day onions: the longest day near 82412 is 15 h 35 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 82412 change?

Yes. The 2012 USDA map put 82412 in zone 4b; the 2023 map puts it in zone 5a. The newer map uses 1991–2020 data and more weather stations.