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

Planting zone for 83429 — Island Park, ID

ZIP code 83429 (Island Park, Fremont County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is June 15 and the first fall frost September 10.

Where ZIP 83429 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.

Zone4a−30 to −25 °F

Coldest night−34.4 to −31.7 °C

Last frostJun 15

First frostSep 10

2012 zone3b

Was 3b 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 4a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Island Park, ID…

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 Island Park, ID

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 15median — 50% chance of a later frost

Safe for tender plantsJuly 7only 10% chance of frost after

First fall frostSeptember 10median — 10% chance by Aug 25

Growing season87 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 24 and returns around September 26.

From the NOAA station Hebgen Dam, MT — 27 miles away, elevation 6,490 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 83429

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · May 4 – May 18

SpinachSow outdoors · May 4 – May 25

Broccoli, cabbageStart indoors · Apr 6 – Apr 20

Broccoli, cabbageTransplant · May 25 – Jun 8

Onion setsPlant outdoors · May 18 – Jun 1

PotatoesPlant outdoors · May 25 – Jun 8

LettuceSow outdoors · May 18 – Jun 1

Carrots, beetsSow outdoors · May 25 – Jun 8

TomatoesStart indoors · Apr 20 – May 4

TomatoesTransplant · Jun 22 – Jul 6

Peppers, eggplantStart indoors · Apr 6 – Apr 20

Peppers, eggplantTransplant · Jun 29 – Jul 13

BeansSow outdoors · Jun 22 – Jul 6

Sweet cornSow outdoors · Jun 22 – Jul 6

Cucumbers, squashSow outdoors · Jun 22 – Jul 6

Fall lettuce, spinachSow outdoors · Jul 16 – Jul 30

GarlicPlant cloves · Aug 27 – Oct 1

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 15) and first fall frost (Sep 10) 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 83429 came on Apr 23 — 15 days earlier than the 1991–2020 average (May 8).

average
May 82026
Apr 23

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 4a in Idaho

408 plants native to the lower 48 states, recorded in Idaho, and rated by the USDA to survive −30 °F or colder — the bottom of zone 4a. 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 Island Park, ID.

Soil in Island Park, ID

The soil mapped at the center of ZIP 83429 is Flatstone — slightly decomposed plant material, well drained.

TextureSlightly decomposed plant materialtop layer

pH6.5neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter75%high

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Flatstone-Koffgo complex, 2 to 15 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 83429; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Island Park, ID

Summer high77 °Faverage high, July

Winter low6 °Faverage low, January

Hot days3days a year at 90 °F or more

Freezing nights247nights a year at 32 °F or less

Growing degree days833base 50 °F — the season’s usable heat

Longest day15 h 33 mindaylight on June 21

Shortest day8 h 50 mindaylight on December 21

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

Precipitation46.1 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: Island Park, ID (4 mi away); precipitation: White Elephant, ID (4 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.

834334a

Macks Inn, ID · 3 mi

597584b

West Yellowstone, MT · 24 mi

Saint Anthony, ID · 36 mi

Idaho planting zones →

Questions about 83429

What planting zone is ZIP code 83429?

ZIP code 83429 (Island Park, ID) is in USDA hardiness zone 4a on the 2023 map: the coldest night of an average winter reaches −30 to −25 °F (−34.4 to −31.7 °C).

When is the last frost in Island Park, ID?

The median last spring frost (32 °F) near 83429 is June 15; after July 7 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Hebgen Dam station.

When is the first frost in Island Park, ID?

The median first fall frost near 83429 is September 10, giving a median frost-free growing season of 87 days.

When should I plant tomatoes in 83429?

Start tomato seeds indoors around Apr 20 – May 4 and set transplants outside around Jun 22 – Jul 6, one to three weeks after the median last frost.

How much rain and snow does 83429 get?

About 46.1 inches of precipitation a year (NOAA 1991–2020 normals, White Elephant station).

How hot do summers get in Island Park, ID?

The average high peaks at 77 °F in July, with about 3 days a year at 90 °F or more.

What kind of soil does 83429 have?

The USDA soil survey maps Flatstone at the center of ZIP 83429: slightly decomposed plant material, well drained, pH about 6.5 (neutral).

Did spring come early in Island Park, ID in 2026?

Spring leaf-out near 83429 came on Apr 23 in 2026, 15 days earlier than the 1991–2020 average (May 8), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Island Park, ID?

Long-day onions: the longest day near 83429 is 15 h 33 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 83429 change?

Yes. The 2012 USDA map put 83429 in zone 3b; the 2023 map puts it in zone 4a. The newer map uses 1991–2020 data and more weather stations.