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

Planting zone for 83868 — Smelterville, ID

ZIP code 83868 (Smelterville, Shoshone County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is May 14 and the first fall frost September 26.

Where ZIP 83868 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.

Zone6b−5 to 0 °F
Coldest night−20.6 to −17.8 °C
Last frostMay 14
First frostSep 26
2012 zone6b

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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Smelterville, 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 Smelterville, ID

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 14median — 50% chance of a later frost
Safe for tender plantsJune 3only 10% chance of frost after
First fall frostSeptember 26median — 10% chance by Sep 9
Growing season131 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 30 and returns around October 8.

From the NOAA station Kellogg, ID — 3 miles away, elevation 2,379 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 83868

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 2 – Apr 16
SpinachSow outdoors · Apr 2 – Apr 23
Broccoli, cabbageStart indoors · Mar 5 – Mar 19
Broccoli, cabbageTransplant · Apr 23 – May 7
Onion setsPlant outdoors · Apr 16 – Apr 30
PotatoesPlant outdoors · Apr 23 – May 7
LettuceSow outdoors · Apr 16 – Apr 30
Carrots, beetsSow outdoors · Apr 23 – May 7
TomatoesStart indoors · Mar 19 – Apr 2
TomatoesTransplant · May 21 – Jun 4
Peppers, eggplantStart indoors · Mar 5 – Mar 19
Peppers, eggplantTransplant · May 28 – Jun 11
BeansSow outdoors · May 21 – Jun 4
Sweet cornSow outdoors · May 21 – Jun 4
Cucumbers, squashSow outdoors · May 21 – Jun 4
Fall lettuce, spinachSow outdoors · Aug 1 – Aug 15
GarlicPlant cloves · Sep 12 – Oct 17
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 14) and first fall frost (Sep 26) 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 83868 came on Apr 3 — 26 days earlier than the 1991–2020 average (Apr 29).

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 6b in Idaho

570 plants native to the lower 48 states, recorded in Idaho, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. Each links to its USDA PLANTS profile.

Trees 30

balsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fblue spruce100 ft · blooms late spring · medium shade tolerance · to −38 °Fboxelder60 ft · blooms early spring · low shade tolerance · to −46 °FDouglas-fir200 ft · blooms mid spring · medium shade tolerance · to −33 °FEngelmann spruce120 ft · blooms late spring · low shade tolerance · to −50 °F

Shrubs 98

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °Falderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °FBarclay's willow15 ft · high shade tolerance · to −43 °Fbeaked hazelnut15 ft · blooms early spring · low shade tolerance · to −47 °F

Wildflowers & perennials 276

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °F

Grasses 154

Alaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °Falkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °FAlpine Meadow-Foxtail0.5 ft · blooms mid spring · medium shade tolerance · to −33 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Fanalogue sedge1.5 ft · blooms late spring · medium shade tolerance · to −38 °F

Vines 1

western white clematis1 ft · blooms mid summer · medium shade tolerance · to −38 °F

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 Smelterville, ID.

Soil in Smelterville, ID

The soil mapped at the center of ZIP 83868 is Honeyjones — slightly decomposed plant material, well drained.

TextureSlightly decomposed plant materialtop layer
pH5.0strongly acidic; 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: Honeyjones-Ahrs association, moderately acid, 35 to 75 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 83868; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Smelterville, ID

Summer high85 °Faverage high, July
Winter low22 °Faverage low, January
Hot days21days a year at 90 °F or more
Freezing nights147nights a year at 32 °F or less
Growing degree days1,843base 50 °F — the season’s usable heat
Longest day15 h 58 mindaylight on June 21
Shortest day8 h 26 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation33.9 inper year, rain and melted snow
Snowfall52 inper year

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 37 °F, low 22 °F 37°22° JanFebruary: average high 42 °F, low 23 °F 42°23° FebMarch: average high 50 °F, low 27 °F 50°27° MarApril: average high 58 °F, low 32 °F 58°32° AprMay: average high 69 °F, low 40 °F 69°40° MayJune: average high 75 °F, low 46 °F 75°46° JunJuly: average high 85 °F, low 51 °F 85°51° JulAugust: average high 84 °F, low 49 °F 84°49° AugSeptember: average high 73 °F, low 41 °F 73°41° SepOctober: average high 58 °F, low 33 °F 58°33° OctNovember: average high 44 °F, low 27 °F 44°27° NovDecember: average high 36 °F, low 22 °F 36°22° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 4.29 in precipitation, 15.1 in snowfall 4.3❄15 JanFebruary: 3.06 in precipitation, 12 in snowfall 3.1❄12 FebMarch: 3.66 in precipitation, 6.4 in snowfall 3.7❄6 MarApril: 2.89 in precipitation, 0.7 in snowfall 2.9❄1 AprMay: 2.88 in precipitation 2.9 MayJune: 2.73 in precipitation 2.7 JunJuly: 1.15 in precipitation 1.1 JulAugust: 0.82 in precipitation 0.8 AugSeptember: 1.32 in precipitation 1.3 SepOctober: 3.11 in precipitation 3.1 OctNovember: 4.55 in precipitation, 4.4 in snowfall 4.5❄4 NovDecember: 3.45 in precipitation, 13.8 in snowfall 3.5❄14 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Kellogg, ID (3 mi away); precipitation: Kellogg, ID (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

838376b
Kellogg, ID · 4 mi
838506b
Pinehurst, ID · 5 mi
838396b
Kingston, ID · 7 mi
838496b
Osburn, ID · 9 mi
838676b
Silverton, ID · 11 mi
838106b
Cataldo, ID · 13 mi
838086b
Calder, ID · 15 mi
838736b
Wallace, ID · 16 mi

Idaho planting zones →

Questions about 83868

What planting zone is ZIP code 83868?

ZIP code 83868 (Smelterville, ID) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Smelterville, ID?

The median last spring frost (32 °F) near 83868 is May 14; after June 3 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Kellogg station.

When is the first frost in Smelterville, ID?

The median first fall frost near 83868 is September 26, giving a median frost-free growing season of 131 days.

When should I plant tomatoes in 83868?

Start tomato seeds indoors around Mar 19 – Apr 2 and set transplants outside around May 21 – Jun 4, one to three weeks after the median last frost.

How much rain and snow does 83868 get?

About 33.9 inches of precipitation a year and 52 inches of snowfall (NOAA 1991–2020 normals, Kellogg station).

How hot do summers get in Smelterville, ID?

The average high peaks at 85 °F in July, with about 21 days a year at 90 °F or more.

What kind of soil does 83868 have?

The USDA soil survey maps Honeyjones at the center of ZIP 83868: slightly decomposed plant material, well drained, pH about 5.0 (strongly acidic).

Did spring come early in Smelterville, ID in 2026?

Spring leaf-out near 83868 came on Apr 3 in 2026, 26 days earlier than the 1991–2020 average (Apr 29), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Smelterville, ID?

Long-day onions: the longest day near 83868 is 15 h 58 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).