Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for Jackson, WY

Jackson, WY is in USDA zone 4b across its 2 ZIP codes. The median last spring frost is June 20 and the first fall frost August 31.

Jackson on the zone map

Outlined: its 1 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.

Zone4b−25 to −20 °F

ZIP codes2

Last frostJun 20

First frostAug 31

Growing season70 days

4b 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Jackson, 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 Jackson, WY

JanFebMarAprMayJunJulAugSepOctNovDec

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

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

Safe for tender plantsJuly 9only 10% chance of frost after

First fall frostAugust 31median — 10% chance by Aug 12

Growing season70 daysfrost-free, median

A hard freeze (28 °F) usually ends around June 2 and returns around September 13.

From the NOAA station Moose, WY, elevation 6,444 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 Jackson

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · May 9 – May 23

SpinachSow outdoors · May 9 – May 30

Broccoli, cabbageStart indoors · Apr 11 – Apr 25

Broccoli, cabbageTransplant · May 30 – Jun 13

Onion setsPlant outdoors · May 23 – Jun 6

PotatoesPlant outdoors · May 30 – Jun 13

LettuceSow outdoors · May 23 – Jun 6

Carrots, beetsSow outdoors · May 30 – Jun 13

TomatoesStart indoors · Apr 25 – May 9

TomatoesTransplant · Jun 27 – Jul 11

Peppers, eggplantStart indoors · Apr 11 – Apr 25

Peppers, eggplantTransplant · Jul 4 – Jul 18

BeansSow outdoors · Jun 27 – Jul 11

Sweet cornSow outdoors · Jun 27 – Jul 11

Cucumbers, squashSow outdoors · Jun 27 – Jul 11

Fall lettuce, spinachSow outdoors · Jul 6 – Jul 20

GarlicPlant cloves · Aug 17 – Sep 21

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 20) and first fall frost (Aug 31) 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 83002 came on Apr 7 — 28 days earlier than the 1991–2020 average (May 5).

average
May 52026
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.

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 Jackson, WY.

Soil in Jackson, WY

The soil mapped at the center of ZIP 83002 is Greyback — gravelly loam, somewhat excessively drained.

TextureGravelly loama good balance for most vegetables

pH7.5slightly alkaline; most vegetables like 6.0–7.0

DrainageSomewhat excessively drainednatural drainage class

Organic matter2%moderate

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Greyback gravelly loam, 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 83002; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Jackson, WY

Summer high79 °Faverage high, July

Winter low6 °Faverage low, January

Hot days5days a year at 90 °F or more

Freezing nights236nights a year at 32 °F or less

Growing degree days880base 50 °F — the season’s usable heat

Longest day15 h 25 mindaylight on June 21

Shortest day8 h 57 mindaylight on December 21

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

Precipitation17.6 inper year, rain and melted snow

Snowfall78 inper year

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Jackson, WY (within 1 mile); precipitation: Jackson, WY (within 1 mile). Daylight is calculated from latitude.

ZIP codes in Jackson

Wyoming planting zones →

Questions about Jackson

What planting zone is Jackson, WY?

Jackson, WY is in USDA hardiness zone 4b on the 2023 map (4b: −25 to −20 °F).

When is the last frost in Jackson, WY?

The median last spring frost is June 20 and the median first fall frost is August 31 (NOAA 1991–2020 normals, Moose station).

When can I plant a garden in Jackson, WY?

Cool-season crops like peas and spinach go in around May 9 – May 30; tomatoes, peppers, beans and squash after about Jun 27, once frost risk has passed.

What kind of onions grow in Jackson, WY?

Long-day onions: the longest day is 15 h 25 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Jackson, WY get?

About 17.6 inches of precipitation a year and 78 inches of snowfall (NOAA 1991–2020 normals).