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

Planting zone for Evanston, WY

Evanston, WY is in USDA zone 5a across its 2 ZIP codes. The median last spring frost is June 14 and the first fall frost September 9.

Evanston 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.

Zone5a−20 to −15 °F

ZIP codes2

Last frostJun 14

First frostSep 9

Growing season84 days

5a 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Evanston, 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 Evanston, WY

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 14median — 50% chance of a later frost

Safe for tender plantsJuly 1only 10% chance of frost after

First fall frostSeptember 9median — 10% chance by Aug 23

Growing season84 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 30 and returns around September 20.

From the NOAA station Mtn View, WY, elevation 6,802 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 Evanston

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · May 3 – May 17

SpinachSow outdoors · May 3 – May 24

Broccoli, cabbageStart indoors · Apr 5 – Apr 19

Broccoli, cabbageTransplant · May 24 – Jun 7

Onion setsPlant outdoors · May 17 – May 31

PotatoesPlant outdoors · May 24 – Jun 7

LettuceSow outdoors · May 17 – May 31

Carrots, beetsSow outdoors · May 24 – Jun 7

TomatoesStart indoors · Apr 19 – May 3

TomatoesTransplant · Jun 21 – Jul 5

Peppers, eggplantStart indoors · Apr 5 – Apr 19

Peppers, eggplantTransplant · Jun 28 – Jul 12

BeansSow outdoors · Jun 21 – Jul 5

Sweet cornSow outdoors · Jun 21 – Jul 5

Cucumbers, squashSow outdoors · Jun 21 – Jul 5

Fall lettuce, spinachSow outdoors · Jul 15 – Jul 29

GarlicPlant cloves · Aug 26 – Sep 30

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 14) and first fall frost (Sep 9) 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 82931 came on Apr 3 — 25 days earlier than the 1991–2020 average (Apr 28).

average
Apr 282026
Apr 3

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.

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 Evanston, WY.

Soil in Evanston, WY

The soil mapped at the center of ZIP 82931 is Almaholt - draft — loam, well drained.

TextureLoama good balance for most vegetables

pH8.0alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Almaholt-Roundor-High loams, 3 to 30 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 82931; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Evanston, WY

Summer high81 °Faverage high, July

Winter low11 °Faverage low, January

Hot days2days a year at 90 °F or more

Freezing nights210nights a year at 32 °F or less

Growing degree days1,359base 50 °F — the season’s usable heat

Longest day15 h 08 mindaylight on June 21

Shortest day9 h 13 mindaylight on December 21

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

Precipitation12.1 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Evanston 1 E, WY (2 mi away); precipitation: Evanston 1 E, WY (2 mi away). Daylight is calculated from latitude.

ZIP codes in Evanston

Wyoming planting zones →

Questions about Evanston

What planting zone is Evanston, WY?

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

When is the last frost in Evanston, WY?

The median last spring frost is June 14 and the median first fall frost is September 9 (NOAA 1991–2020 normals, Mtn View station).

When can I plant a garden in Evanston, WY?

Cool-season crops like peas and spinach go in around May 3 – May 24; tomatoes, peppers, beans and squash after about Jun 21, once frost risk has passed.

What kind of onions grow in Evanston, WY?

Long-day onions: the longest day is 15 h 08 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Evanston, WY get?

About 12.1 inches of precipitation a year (NOAA 1991–2020 normals).