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

Planting zone for 83203 — Fort Hall, ID

ZIP code 83203 (Fort Hall, Bingham County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 20 and the first fall frost September 20.

Where ZIP 83203 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.

Zone5b−15 to −10 °F

Coldest night−26.1 to −23.3 °C

Last frostMay 20

First frostSep 20

2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Fort Hall, 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 Fort Hall, ID

JanFebMarAprMayJunJulAugSepOctNovDec

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

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

Safe for tender plantsJune 12only 10% chance of frost after

First fall frostSeptember 20median — 10% chance by Sep 1

Growing season119 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 6 and returns around October 4.

From the NOAA station Ft Hall 1 Nne, ID — within 1 mile, elevation 4,465 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 83203

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 8 – Apr 22

SpinachSow outdoors · Apr 8 – Apr 29

Broccoli, cabbageStart indoors · Mar 11 – Mar 25

Broccoli, cabbageTransplant · Apr 29 – May 13

Onion setsPlant outdoors · Apr 22 – May 6

PotatoesPlant outdoors · Apr 29 – May 13

LettuceSow outdoors · Apr 22 – May 6

Carrots, beetsSow outdoors · Apr 29 – May 13

TomatoesStart indoors · Mar 25 – Apr 8

TomatoesTransplant · May 27 – Jun 10

Peppers, eggplantStart indoors · Mar 11 – Mar 25

Peppers, eggplantTransplant · Jun 3 – Jun 17

BeansSow outdoors · May 27 – Jun 10

Sweet cornSow outdoors · May 27 – Jun 10

Cucumbers, squashSow outdoors · May 27 – Jun 10

Fall lettuce, spinachSow outdoors · Jul 26 – Aug 9

GarlicPlant cloves · Sep 6 – Oct 11

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 20) and first fall frost (Sep 20) 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 83203 came on Mar 19 — 20 days earlier than the 1991–2020 average (Apr 8).

average
Apr 82026
Mar 19

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 5b in Idaho

553 plants native to the lower 48 states, recorded in Idaho, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. 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 Fort Hall, ID.

Soil in Fort Hall, ID

The soil mapped at the center of ZIP 83203 is Parehat — silt loam, somewhat poorly drained.

TextureSilt loama good balance for most vegetables

pH8.2alkaline; most vegetables like 6.0–7.0

DrainageSomewhat poorly drainedconsider raised beds

Organic matter3%moderate

Hydrologic groupCwater soaks in slowly

Farmland classFarmland of statewide importance, if irrigated and drainedUSDA classification

Map unit: Parehat rarely flooded-Snake-Tickason complex, 0 to 5 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 83203; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Fort Hall, ID

Summer high86 °Faverage high, July

Winter low15 °Faverage low, January

Hot days26days a year at 90 °F or more

Freezing nights186nights a year at 32 °F or less

Growing degree days1,917base 50 °F — the season’s usable heat

Longest day15 h 22 mindaylight on June 21

Shortest day9 h 00 mindaylight on December 21

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

Precipitation10.5 inper year, rain and melted snow

Snowfall28 inper year; 64 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Ft Hall 1 Nne, ID (within 1 mile); precipitation: Ft Hall 1 Nne, ID (within 1 mile). 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.

Pocatello, ID · 11 mi

832096a

Pocatello, ID · 12 mi

832775b

Springfield, ID · 13 mi

832056a

Pocatello, ID · 15 mi

832046a

Pocatello, ID · 16 mi

832456a

Inkom, ID · 16 mi

Idaho planting zones →

Questions about 83203

What planting zone is ZIP code 83203?

ZIP code 83203 (Fort Hall, ID) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Fort Hall, ID?

The median last spring frost (32 °F) near 83203 is May 20; after June 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Ft Hall 1 Nne station.

When is the first frost in Fort Hall, ID?

The median first fall frost near 83203 is September 20, giving a median frost-free growing season of 119 days.

When should I plant tomatoes in 83203?

Start tomato seeds indoors around Mar 25 – Apr 8 and set transplants outside around May 27 – Jun 10, one to three weeks after the median last frost.

How much rain and snow does 83203 get?

About 10.5 inches of precipitation a year and 28 inches of snowfall (NOAA 1991–2020 normals, Ft Hall 1 Nne station).

How hot do summers get in Fort Hall, ID?

The average high peaks at 86 °F in July, with about 26 days a year at 90 °F or more.

What kind of soil does 83203 have?

The USDA soil survey maps Parehat at the center of ZIP 83203: silt loam, somewhat poorly drained, pH about 8.2 (alkaline).

Did spring come early in Fort Hall, ID in 2026?

Spring leaf-out near 83203 came on Mar 19 in 2026, 20 days earlier than the 1991–2020 average (Apr 8), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Fort Hall, ID?

Long-day onions: the longest day near 83203 is 15 h 22 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).