Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 30, 2026

Planting zone for 82730 — Upton, WY

ZIP code 82730 (Upton, Weston County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 20 and the first fall frost September 23.

Where ZIP 82730 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 20

First frostSep 23

2012 zone4a

Was 4a 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 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Upton, 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 Upton, WY

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMay 20median — 50% chance of a later frost

Safe for tender plantsJune 4only 10% chance of frost after

First fall frostSeptember 23median — 10% chance by Sep 7

Growing season123 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 9 and returns around October 2.

From the NOAA station Upton, WY — 6 miles away, elevation 4,321 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 82730

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 8 – Apr 22

SpinachSow outdoors · Apr 8 – Apr 29

Broccoli, cabbageStart indoors · Mar 11 – Mar 25

Broccoli, cabbageTransplant · Apr 29 – May 13

Onion setsPlant outdoors · Apr 22 – May 6

PotatoesPlant outdoors · Apr 29 – May 13

LettuceSow outdoors · Apr 22 – May 6

Carrots, beetsSow outdoors · Apr 29 – May 13

TomatoesStart indoors · Mar 25 – Apr 8

TomatoesTransplant · May 27 – Jun 10

Peppers, eggplantStart indoors · Mar 11 – Mar 25

Peppers, eggplantTransplant · Jun 3 – Jun 17

BeansSow outdoors · May 27 – Jun 10

Sweet cornSow outdoors · May 27 – Jun 10

Cucumbers, squashSow outdoors · May 27 – Jun 10

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 20) 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 82730 came on Mar 22 — 21 days earlier than the 1991–2020 average (Apr 12).

average
Apr 122026
Mar 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 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.

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 Upton, WY.

Soil in Upton, WY

The soil mapped at the center of ZIP 82730 is Terro — sandy loam, well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding

pH7.2neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Terro-Turnercrest sandy loams, 2 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 82730; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Upton, WY

Summer high87 °Faverage high, July

Winter low10 °Faverage low, January

Hot days31days a year at 90 °F or more

Freezing nights182nights a year at 32 °F or less

Growing degree days2,258base 50 °F — the season’s usable heat

Longest day15 h 30 mindaylight on June 21

Shortest day8 h 53 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation16.2 inper year, rain and melted snow

Snowfall46 inper year; 77 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Upton, WY (6 mi away); precipitation: Upton, WY (6 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 · 15 mi

827014b

Newcastle, WY · 27 mi

827294b

Sundance, WY · 29 mi

827214b

Moorcroft, WY · 30 mi

827274b

Rozet, WY · 31 mi

827144b

Devils Tower, WY · 35 mi

Wyoming planting zones →

Questions about 82730

What planting zone is ZIP code 82730?

ZIP code 82730 (Upton, 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 Upton, WY?

The median last spring frost (32 °F) near 82730 is May 20; after June 4 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Upton station.

When is the first frost in Upton, WY?

The median first fall frost near 82730 is September 23, giving a median frost-free growing season of 123 days.

When should I plant tomatoes in 82730?

Start tomato seeds indoors around Mar 25 – Apr 8 and set transplants outside around May 27 – Jun 10, one to three weeks after the median last frost.

How much rain and snow does 82730 get?

About 16.2 inches of precipitation a year and 46 inches of snowfall (NOAA 1991–2020 normals, Upton station).

How hot do summers get in Upton, WY?

The average high peaks at 87 °F in July, with about 31 days a year at 90 °F or more.

What kind of soil does 82730 have?

The USDA soil survey maps Terro at the center of ZIP 82730: sandy loam, well drained, pH about 7.2 (neutral).

Did spring come early in Upton, WY in 2026?

Spring leaf-out near 82730 came on Mar 22 in 2026, 21 days earlier than the 1991–2020 average (Apr 12), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Upton, WY?

Long-day onions: the longest day near 82730 is 15 h 30 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 82730 change?

Yes. The 2012 USDA map put 82730 in zone 4a; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.