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

Planting zone for 82083 — Rock River, WY

ZIP code 82083 (Rock River, Albany County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is June 1 and the first fall frost September 8.

Where ZIP 82083 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 frostJun 1
First frostSep 8
2012 zone4b

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 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Rock River, 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 Rock River, WY

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostJune 1median — 50% chance of a later frost
Safe for tender plantsJune 19only 10% chance of frost after
First fall frostSeptember 8median — 10% chance by Aug 28
Growing season97 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 19 and returns around September 17.

From the NOAA station Medicine Bow, WY — 16 miles away, elevation 6,634 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 82083

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 20 – May 4
SpinachSow outdoors · Apr 20 – May 11
Broccoli, cabbageStart indoors · Mar 23 – Apr 6
Broccoli, cabbageTransplant · May 11 – May 25
Onion setsPlant outdoors · May 4 – May 18
PotatoesPlant outdoors · May 11 – May 25
LettuceSow outdoors · May 4 – May 18
Carrots, beetsSow outdoors · May 11 – May 25
TomatoesStart indoors · Apr 6 – Apr 20
TomatoesTransplant · Jun 8 – Jun 22
Peppers, eggplantStart indoors · Mar 23 – Apr 6
Peppers, eggplantTransplant · Jun 15 – Jun 29
BeansSow outdoors · Jun 8 – Jun 22
Sweet cornSow outdoors · Jun 8 – Jun 22
Cucumbers, squashSow outdoors · Jun 8 – Jun 22
Fall lettuce, spinachSow outdoors · Jul 14 – Jul 28
GarlicPlant cloves · Aug 25 – Sep 29
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 1) and first fall frost (Sep 8) 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 82083 came on Mar 31 — 25 days earlier than the 1991–2020 average (Apr 25).

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 Rock River, WY.

Soil in Rock River, WY

The soil mapped at the center of ZIP 82083 is Redrob — loam, poorly drained.

TextureLoama good balance for most vegetables
pH8.2alkaline; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter2%moderate
Hydrologic groupB/Dmoderate when drained; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Redrob, frequently flooded-Grenoble-Redrob complex, 0 to 3 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 82083; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Rock River, WY

Summer high85 °Faverage high, July
Winter low10 °Faverage low, January
Hot days10days a year at 90 °F or more
Freezing nights209nights a year at 32 °F or less
Growing degree days1,565base 50 °F — the season’s usable heat
Longest day15 h 13 mindaylight on June 21
Shortest day9 h 09 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation18 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 10 °F 31°10° JanFebruary: average high 35 °F, low 12 °F 35°12° FebMarch: average high 46 °F, low 18 °F 46°18° MarApril: average high 55 °F, low 25 °F 55°25° AprMay: average high 65 °F, low 33 °F 65°33° MayJune: average high 77 °F, low 43 °F 77°43° JunJuly: average high 85 °F, low 48 °F 85°48° JulAugust: average high 83 °F, low 46 °F 83°46° AugSeptember: average high 74 °F, low 36 °F 74°36° SepOctober: average high 59 °F, low 27 °F 59°27° OctNovember: average high 43 °F, low 18 °F 43°18° NovDecember: average high 33 °F, low 11 °F 33°11° Dec

Precipitation by month inches

0″1″2″3″January: 0.77 in precipitation 0.8 JanFebruary: 1.15 in precipitation 1.1 FebMarch: 1.57 in precipitation 1.6 MarApril: 1.97 in precipitation 2.0 AprMay: 2.62 in precipitation 2.6 MayJune: 1.77 in precipitation 1.8 JunJuly: 1.40 in precipitation 1.4 JulAugust: 1.23 in precipitation 1.2 AugSeptember: 1.55 in precipitation 1.6 SepOctober: 1.72 in precipitation 1.7 OctNovember: 1.12 in precipitation 1.1 NovDecember: 1.10 in precipitation 1.1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Medicine Bow, WY (16 mi away); precipitation: Rock River 9.6 Wsw, WY (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

820514a
Bosler, WY · 20 mi
823294a
Medicine Bow, WY · 23 mi
823245a
Elk Mountain, WY · 23 mi
820555a
Centennial, WY · 28 mi
820724a
Laramie, WY · 31 mi
820585a
Garrett, WY · 36 mi
820704b
Laramie, WY · 36 mi
820735b
Laramie, WY · 48 mi

Wyoming planting zones →

Questions about 82083

What planting zone is ZIP code 82083?

ZIP code 82083 (Rock River, 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 Rock River, WY?

The median last spring frost (32 °F) near 82083 is June 1; after June 19 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Medicine Bow station.

When is the first frost in Rock River, WY?

The median first fall frost near 82083 is September 8, giving a median frost-free growing season of 97 days.

When should I plant tomatoes in 82083?

Start tomato seeds indoors around Apr 6 – Apr 20 and set transplants outside around Jun 8 – Jun 22, one to three weeks after the median last frost.

How much rain and snow does 82083 get?

About 18 inches of precipitation a year (NOAA 1991–2020 normals, Rock River 9.6 Wsw station).

How hot do summers get in Rock River, WY?

The average high peaks at 85 °F in July, with about 10 days a year at 90 °F or more.

What kind of soil does 82083 have?

The USDA soil survey maps Redrob at the center of ZIP 82083: loam, poorly drained, pH about 8.2 (alkaline).

Did spring come early in Rock River, WY in 2026?

Spring leaf-out near 82083 came on Mar 31 in 2026, 25 days earlier than the 1991–2020 average (Apr 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Rock River, WY?

Long-day onions: the longest day near 82083 is 15 h 13 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).