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

Planting zone for 83350 — Rupert, ID

ZIP code 83350 (Rupert, Minidoka County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 16 and the first fall frost October 1.

Where ZIP 83350 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.

Zone6a−10 to −5 °F

Coldest night−23.3 to −20.6 °C

Last frostMay 16

First frostOct 1

2012 zone6a

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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Rupert, 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 Rupert, ID

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 16median — 50% chance of a later frost

Safe for tender plantsJune 5only 10% chance of frost after

First fall frostOctober 1median — 10% chance by Sep 13

Growing season136 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 2 and returns around October 15.

From the NOAA station Minidoka Dam, ID — 6 miles away, elevation 4,164 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 83350

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 4 – Apr 18

SpinachSow outdoors · Apr 4 – Apr 25

Broccoli, cabbageStart indoors · Mar 7 – Mar 21

Broccoli, cabbageTransplant · Apr 25 – May 9

Onion setsPlant outdoors · Apr 18 – May 2

PotatoesPlant outdoors · Apr 25 – May 9

LettuceSow outdoors · Apr 18 – May 2

Carrots, beetsSow outdoors · Apr 25 – May 9

TomatoesStart indoors · Mar 21 – Apr 4

TomatoesTransplant · May 23 – Jun 6

Peppers, eggplantStart indoors · Mar 7 – Mar 21

Peppers, eggplantTransplant · May 30 – Jun 13

BeansSow outdoors · May 23 – Jun 6

Sweet cornSow outdoors · May 23 – Jun 6

Cucumbers, squashSow outdoors · May 23 – Jun 6

Fall lettuce, spinachSow outdoors · Aug 6 – Aug 20

GarlicPlant cloves · Sep 17 – Oct 22

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 16) and first fall frost (Oct 1) 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 83350 came on Mar 14 — 21 days earlier than the 1991–2020 average (Apr 4).

average
Apr 42026
Mar 14

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 6a in Idaho

567 plants native to the lower 48 states, recorded in Idaho, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. 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 Rupert, ID.

Soil in Rupert, ID

The soil mapped at the center of ZIP 83350 is Portneuf — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH7.9alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classPrime farmland if irrigated and reclaimed of excess salts and sodiumUSDA classification

Map unit: Portneuf silt loam, 1 to 4 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 83350; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Rupert, ID

Summer high89 °Faverage high, July

Winter low18 °Faverage low, January

Hot days39days a year at 90 °F or more

Freezing nights166nights a year at 32 °F or less

Growing degree days2,425base 50 °F — the season’s usable heat

Longest day15 h 20 mindaylight on June 21

Shortest day9 h 02 mindaylight on December 21

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

Precipitation9.8 inper year, rain and melted snow

Snowfall21 inper year

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Minidoka Dam, ID (6 mi away); precipitation: Minidoka Dam, ID (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

American Falls, ID · 27 mi

Idaho planting zones →

Questions about 83350

What planting zone is ZIP code 83350?

ZIP code 83350 (Rupert, ID) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Rupert, ID?

The median last spring frost (32 °F) near 83350 is May 16; after June 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Minidoka Dam station.

When is the first frost in Rupert, ID?

The median first fall frost near 83350 is October 1, giving a median frost-free growing season of 136 days.

When should I plant tomatoes in 83350?

Start tomato seeds indoors around Mar 21 – Apr 4 and set transplants outside around May 23 – Jun 6, one to three weeks after the median last frost.

How much rain and snow does 83350 get?

About 9.8 inches of precipitation a year and 21 inches of snowfall (NOAA 1991–2020 normals, Minidoka Dam station).

How hot do summers get in Rupert, ID?

The average high peaks at 89 °F in July, with about 39 days a year at 90 °F or more.

What kind of soil does 83350 have?

The USDA soil survey maps Portneuf at the center of ZIP 83350: silt loam, well drained, pH about 7.9 (alkaline).

Did spring come early in Rupert, ID in 2026?

Spring leaf-out near 83350 came on Mar 14 in 2026, 21 days earlier than the 1991–2020 average (Apr 4), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Rupert, ID?

Long-day onions: the longest day near 83350 is 15 h 20 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).