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

Planting zone for Gillette, WY

Gillette, WY is in USDA zone 5a across its 3 ZIP codes. The median last spring frost is May 21 and the first fall frost September 23.

Gillette on the zone map

Outlined: its 2 ZIP code areas · 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
ZIP codes3
Last frostMay 21
First frostSep 23
Growing season123 days

5a 3 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Gillette, 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 Gillette, WY

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 21median — 50% chance of a later frost
Safe for tender plantsJune 3only 10% chance of frost after
First fall frostSeptember 23median — 10% chance by Sep 8
Growing season123 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 10 and returns around October 2.

From the NOAA station Echeta 2 Nw, WY, elevation 4,000 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 Gillette

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 9 – Apr 23
SpinachSow outdoors · Apr 9 – Apr 30
Broccoli, cabbageStart indoors · Mar 12 – Mar 26
Broccoli, cabbageTransplant · Apr 30 – May 14
Onion setsPlant outdoors · Apr 23 – May 7
PotatoesPlant outdoors · Apr 30 – May 14
LettuceSow outdoors · Apr 23 – May 7
Carrots, beetsSow outdoors · Apr 30 – May 14
TomatoesStart indoors · Mar 26 – Apr 9
TomatoesTransplant · May 28 – Jun 11
Peppers, eggplantStart indoors · Mar 12 – Mar 26
Peppers, eggplantTransplant · Jun 4 – Jun 18
BeansSow outdoors · May 28 – Jun 11
Sweet cornSow outdoors · May 28 – Jun 11
Cucumbers, squashSow outdoors · May 28 – Jun 11
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 21) 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 82717 came on Mar 16 — 26 days earlier than the 1991–2020 average (Apr 11).

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 Gillette, WY.

Soil in Gillette, WY

The soil mapped at the center of ZIP 82717 is Rauzi — fine sandy loam, well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding
pH7.0neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupBwater soaks in moderately
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Rauzi fine sandy loam, 0 to 6 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 82717; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Gillette, WY

Summer high87 °Faverage high, July
Winter low14 °Faverage low, January
Hot days35days a year at 90 °F or more
Freezing nights179nights a year at 32 °F or less
Growing degree days2,232base 50 °F — the season’s usable heat
Longest day15 h 31 mindaylight on June 21
Shortest day8 h 51 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 36 °F, low 14 °F 36°14° JanFebruary: average high 37 °F, low 15 °F 37°15° FebMarch: average high 48 °F, low 23 °F 48°23° MarApril: average high 55 °F, low 30 °F 55°30° AprMay: average high 65 °F, low 39 °F 65°39° MayJune: average high 77 °F, low 48 °F 77°48° JunJuly: average high 87 °F, low 56 °F 87°56° JulAugust: average high 86 °F, low 54 °F 86°54° AugSeptember: average high 75 °F, low 44 °F 75°44° SepOctober: average high 59 °F, low 32 °F 59°32° OctNovember: average high 46 °F, low 22 °F 46°22° NovDecember: average high 36 °F, low 15 °F 36°15° Dec

Precipitation by month inches

0″1″2″3″4″January: 0.57 in precipitation 0.6 JanFebruary: 0.78 in precipitation 0.8 FebMarch: 0.98 in precipitation 1.0 MarApril: 2.23 in precipitation 2.2 AprMay: 2.94 in precipitation 2.9 MayJune: 3.12 in precipitation 3.1 JunJuly: 2.05 in precipitation 2.0 JulAugust: 1.22 in precipitation 1.2 AugSeptember: 1.22 in precipitation 1.2 SepOctober: 1.55 in precipitation 1.6 OctNovember: 0.71 in precipitation 0.7 NovDecember: 0.60 in precipitation 0.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Gillette Campbell Airport, WY (3 mi away); precipitation: Gillette 0.5 Ene, WY (within 1 mile). Daylight is calculated from latitude.

ZIP codes in Gillette

827165a
−20 to −15 °F
827175a
−20 to −15 °F
827185a
−20 to −15 °F

Wyoming planting zones →

Questions about Gillette

What planting zone is Gillette, WY?

Gillette, WY is in USDA hardiness zone 5a on the 2023 map (5a: −20 to −15 °F).

When is the last frost in Gillette, WY?

The median last spring frost is May 21 and the median first fall frost is September 23 (NOAA 1991–2020 normals, Echeta 2 Nw station).

When can I plant a garden in Gillette, WY?

Cool-season crops like peas and spinach go in around Apr 9 – Apr 30; tomatoes, peppers, beans and squash after about May 28, once frost risk has passed.

What kind of onions grow in Gillette, WY?

Long-day onions: the longest day is 15 h 31 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Gillette, WY get?

About 18 inches of precipitation a year (NOAA 1991–2020 normals).