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

Planting zone for 82701 — Newcastle, WY

ZIP code 82701 (Newcastle, Weston County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 13 and the first fall frost October 3.

Where ZIP 82701 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.

Zone4b−25 to −20 °F
Coldest night−31.7 to −28.9 °C
Last frostMay 13
First frostOct 3
2012 zone5a

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

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Newcastle, 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 Newcastle, WY

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 13median — 50% chance of a later frost
Safe for tender plantsMay 26only 10% chance of frost after
First fall frostOctober 3median — 10% chance by Sep 17
Growing season143 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 1 and returns around October 11.

From the NOAA station Newcastle, WY — 17 miles away, elevation 4,416 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 82701

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 1 – Apr 15
SpinachSow outdoors · Apr 1 – Apr 22
Broccoli, cabbageStart indoors · Mar 4 – Mar 18
Broccoli, cabbageTransplant · Apr 22 – May 6
Onion setsPlant outdoors · Apr 15 – Apr 29
PotatoesPlant outdoors · Apr 22 – May 6
LettuceSow outdoors · Apr 15 – Apr 29
Carrots, beetsSow outdoors · Apr 22 – May 6
TomatoesStart indoors · Mar 18 – Apr 1
TomatoesTransplant · May 20 – Jun 3
Peppers, eggplantStart indoors · Mar 4 – Mar 18
Peppers, eggplantTransplant · May 27 – Jun 10
BeansSow outdoors · May 20 – Jun 3
Sweet cornSow outdoors · May 20 – Jun 3
Cucumbers, squashSow outdoors · May 20 – Jun 3
Fall lettuce, spinachSow outdoors · Aug 8 – Aug 22
GarlicPlant cloves · Sep 19 – Oct 24
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 13) and first fall frost (Oct 3) 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 82701 came on Mar 17 — 21 days earlier than the 1991–2020 average (Apr 7).

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 4b in Wyoming

495 plants native to the lower 48 states, recorded in Wyoming, and rated by the USDA to survive −25 °F or colder — the bottom of zone 4b. 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 83

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 226

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 152

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 Newcastle, WY.

Soil in Newcastle, WY

The soil mapped at the center of ZIP 82701 is Forkwood — loam, well drained.

TextureLoama good balance for most vegetables
pH7.5slightly alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2.5%moderate
Hydrologic groupBwater soaks in moderately
Farmland classFarmland of statewide importance, if irrigatedUSDA classification

Map unit: Forkwood-Ulm complex, 0 to 10 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 82701; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Newcastle, WY

Summer high87 °Faverage high, July
Winter low14 °Faverage low, January
Hot days34days a year at 90 °F or more
Freezing nights168nights a year at 32 °F or less
Growing degree days2,641base 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)
Precipitation17.2 inper year, rain and melted snow
Snowfall39 inper year; 59 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 35 °F, low 14 °F 35°14° JanFebruary: average high 38 °F, low 16 °F 38°16° FebMarch: average high 48 °F, low 26 °F 48°26° MarApril: average high 57 °F, low 33 °F 57°33° AprMay: average high 66 °F, low 43 °F 66°43° MayJune: average high 78 °F, low 53 °F 78°53° JunJuly: average high 87 °F, low 60 °F 87°60° JulAugust: average high 86 °F, low 59 °F 86°59° AugSeptember: average high 75 °F, low 49 °F 75°49° SepOctober: average high 59 °F, low 36 °F 59°36° OctNovember: average high 45 °F, low 24 °F 45°24° NovDecember: average high 35 °F, low 15 °F 35°15° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″January: 0.51 in precipitation, 6.8 in snowfall 0.5❄7 JanFebruary: 0.67 in precipitation, 7.7 in snowfall 0.7❄8 FebMarch: 0.77 in precipitation, 4.9 in snowfall 0.8❄5 MarApril: 1.70 in precipitation, 5 in snowfall 1.7❄5 AprMay: 2.90 in precipitation, 0.6 in snowfall 2.9❄1 MayJune: 2.68 in precipitation 2.7 JunJuly: 2.54 in precipitation 2.5 JulAugust: 1.82 in precipitation 1.8 AugSeptember: 1.20 in precipitation, 0.2 in snowfall 1.2 SepOctober: 1.24 in precipitation, 1.4 in snowfall 1.2❄1 OctNovember: 0.59 in precipitation, 5.5 in snowfall 0.6❄6 NovDecember: 0.54 in precipitation, 6.8 in snowfall 0.5❄7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Newcastle, WY (17 mi away); precipitation: Newcastle, WY (17 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

827234b
Osage, WY · 21 mi
827304b
Upton, WY · 27 mi
822224b
Lance Creek, WY · 38 mi
577454b
Hill City, SD · 40 mi
577305a
Custer, SD · 41 mi
577354b
Edgemont, SD · 41 mi
577735b
Pringle, SD · 44 mi
827294b
Sundance, WY · 47 mi

Wyoming planting zones →

Questions about 82701

What planting zone is ZIP code 82701?

ZIP code 82701 (Newcastle, WY) is in USDA hardiness zone 4b on the 2023 map: the coldest night of an average winter reaches −25 to −20 °F (−31.7 to −28.9 °C).

When is the last frost in Newcastle, WY?

The median last spring frost (32 °F) near 82701 is May 13; after May 26 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Newcastle station.

When is the first frost in Newcastle, WY?

The median first fall frost near 82701 is October 3, giving a median frost-free growing season of 143 days.

When should I plant tomatoes in 82701?

Start tomato seeds indoors around Mar 18 – Apr 1 and set transplants outside around May 20 – Jun 3, one to three weeks after the median last frost.

How much rain and snow does 82701 get?

About 17.2 inches of precipitation a year and 39 inches of snowfall (NOAA 1991–2020 normals, Newcastle station).

How hot do summers get in Newcastle, WY?

The average high peaks at 87 °F in July, with about 34 days a year at 90 °F or more.

What kind of soil does 82701 have?

The USDA soil survey maps Forkwood at the center of ZIP 82701: loam, well drained, pH about 7.5 (slightly alkaline).

Did spring come early in Newcastle, WY in 2026?

Spring leaf-out near 82701 came on Mar 17 in 2026, 21 days earlier than the 1991–2020 average (Apr 7), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Newcastle, WY?

Long-day onions: the longest day near 82701 is 15 h 27 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 82701 change?

Yes. The 2012 USDA map put 82701 in zone 5a; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.