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

Planting zone for 83465 — Lemhi, ID

ZIP code 83465 (Lemhi, Lemhi County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is June 12 and the first fall frost September 6.

Where ZIP 83465 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 frostJun 12

First frostSep 6

2012 zone5a

Was 5a 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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Lemhi, 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 Lemhi, ID

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 12median — 50% chance of a later frost

Safe for tender plantsJune 29only 10% chance of frost after

First fall frostSeptember 6median — 10% chance by Aug 23

Growing season85 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 20 and returns around September 19.

From the NOAA station May 2sse, ID — 19 miles away, elevation 5,049 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 83465

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · May 1 – May 15

SpinachSow outdoors · May 1 – May 22

Broccoli, cabbageStart indoors · Apr 3 – Apr 17

Broccoli, cabbageTransplant · May 22 – Jun 5

Onion setsPlant outdoors · May 15 – May 29

PotatoesPlant outdoors · May 22 – Jun 5

LettuceSow outdoors · May 15 – May 29

Carrots, beetsSow outdoors · May 22 – Jun 5

TomatoesStart indoors · Apr 17 – May 1

TomatoesTransplant · Jun 19 – Jul 3

Peppers, eggplantStart indoors · Apr 3 – Apr 17

Peppers, eggplantTransplant · Jun 26 – Jul 10

BeansSow outdoors · Jun 19 – Jul 3

Sweet cornSow outdoors · Jun 19 – Jul 3

Cucumbers, squashSow outdoors · Jun 19 – Jul 3

Fall lettuce, spinachSow outdoors · Jul 12 – Jul 26

GarlicPlant cloves · Aug 23 – Sep 27

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 12) and first fall frost (Sep 6) 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 83465 came on Apr 18 — 13 days earlier than the 1991–2020 average (May 1).

average
May 12026
Apr 18

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 Lemhi, ID.

Soil in Lemhi, ID

The soil mapped at the center of ZIP 83465 is Dacont — gravelly loam, well drained.

TextureGravelly loama good balance for most vegetables

pH7.0neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Dacont-Zeebar association, 20 to 50 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 83465; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Lemhi, ID

Summer high83 °Faverage high, July

Winter low5 °Faverage low, January

Hot days9days a year at 90 °F or more

Freezing nights240nights a year at 32 °F or less

Growing degree days1,090base 50 °F — the season’s usable heat

Longest day15 h 35 mindaylight on June 21

Shortest day8 h 47 mindaylight on December 21

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

Precipitation25.9 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: Leadore #2, ID (17 mi away); precipitation: Schwartz Lake, ID (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

2 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

Idaho planting zones →

Questions about 83465

What planting zone is ZIP code 83465?

ZIP code 83465 (Lemhi, 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 Lemhi, ID?

The median last spring frost (32 °F) near 83465 is June 12; after June 29 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, May 2sse station.

When is the first frost in Lemhi, ID?

The median first fall frost near 83465 is September 6, giving a median frost-free growing season of 85 days.

When should I plant tomatoes in 83465?

Start tomato seeds indoors around Apr 17 – May 1 and set transplants outside around Jun 19 – Jul 3, one to three weeks after the median last frost.

How much rain and snow does 83465 get?

About 25.9 inches of precipitation a year (NOAA 1991–2020 normals, Schwartz Lake station).

How hot do summers get in Lemhi, ID?

The average high peaks at 83 °F in July, with about 9 days a year at 90 °F or more.

What kind of soil does 83465 have?

The USDA soil survey maps Dacont at the center of ZIP 83465: gravelly loam, well drained, pH about 7.0 (neutral).

Did spring come early in Lemhi, ID in 2026?

Spring leaf-out near 83465 came on Apr 18 in 2026, 13 days earlier than the 1991–2020 average (May 1), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Lemhi, ID?

Long-day onions: the longest day near 83465 is 15 h 35 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 83465 change?

Yes. The 2012 USDA map put 83465 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.