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

Planting zone for 97842 — Imnaha, OR

ZIP code 97842 (Imnaha, Wallowa County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is June 8 and the first fall frost September 5.

Where ZIP 97842 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 frostJun 8

First frostSep 5

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 Imnaha, OR…

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 Imnaha, OR

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 8median — 50% chance of a later frost

Safe for tender plantsJuly 8only 10% chance of frost after

First fall frostSeptember 5median — 10% chance by Aug 16

Growing season84 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 13 and returns around September 22.

From the NOAA station Enterprise 20 Nne, OR — 19 miles away, elevation 3,281 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 97842

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 27 – May 11

SpinachSow outdoors · Apr 27 – May 18

Broccoli, cabbageStart indoors · Mar 30 – Apr 13

Broccoli, cabbageTransplant · May 18 – Jun 1

Onion setsPlant outdoors · May 11 – May 25

PotatoesPlant outdoors · May 18 – Jun 1

LettuceSow outdoors · May 11 – May 25

Carrots, beetsSow outdoors · May 18 – Jun 1

TomatoesStart indoors · Apr 13 – Apr 27

TomatoesTransplant · Jun 15 – Jun 29

Peppers, eggplantStart indoors · Mar 30 – Apr 13

Peppers, eggplantTransplant · Jun 22 – Jul 6

BeansSow outdoors · Jun 15 – Jun 29

Sweet cornSow outdoors · Jun 15 – Jun 29

Cucumbers, squashSow outdoors · Jun 15 – Jun 29

Fall lettuce, spinachSow outdoors · Jul 11 – Jul 25

GarlicPlant cloves · Aug 22 – Sep 26

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 8) and first fall frost (Sep 5) 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 97842 came on Mar 21 — 24 days earlier than the 1991–2020 average (Apr 14).

average
Apr 142026
Mar 21

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 Oregon

613 plants native to the lower 48 states, recorded in Oregon, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. 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 Imnaha, OR.

Soil in Imnaha, OR

The soil mapped at the center of ZIP 97842 is Vitrandic Argixerolls — gravelly ashy silt loam, well drained.

TextureGravelly ashy silt loama good balance for most vegetables

pH6.5neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter4%moderate

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Vitrandic Argixerolls, dry-Lithic Haploxerolls, very shallow-Lithic Haploxerolls complex, 35 to 70 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 97842; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Imnaha, OR

Summer high89 °Faverage high, August

Winter low18 °Faverage low, January

Hot days40days a year at 90 °F or more

Freezing nights204nights a year at 32 °F or less

Growing degree days1,750base 50 °F — the season’s usable heat

Longest day15 h 42 mindaylight on June 21

Shortest day8 h 41 mindaylight on December 21

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

Precipitation19 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: Enterprise 20 Nne, OR (19 mi away); precipitation: Enterprise 20 Nne, OR (19 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.

978287a

Enterprise, OR · 18 mi

835427a

Lucile, ID · 23 mi

835226b

Cottonwood, ID · 26 mi

835547a

White Bird, ID · 26 mi

Winchester, ID · 32 mi

Oregon planting zones →

Questions about 97842

What planting zone is ZIP code 97842?

ZIP code 97842 (Imnaha, OR) 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 Imnaha, OR?

The median last spring frost (32 °F) near 97842 is June 8; after July 8 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Enterprise 20 Nne station.

When is the first frost in Imnaha, OR?

The median first fall frost near 97842 is September 5, giving a median frost-free growing season of 84 days.

When should I plant tomatoes in 97842?

Start tomato seeds indoors around Apr 13 – Apr 27 and set transplants outside around Jun 15 – Jun 29, one to three weeks after the median last frost.

How much rain and snow does 97842 get?

About 19 inches of precipitation a year (NOAA 1991–2020 normals, Enterprise 20 Nne station).

How hot do summers get in Imnaha, OR?

The average high peaks at 89 °F in August, with about 40 days a year at 90 °F or more.

What kind of soil does 97842 have?

The USDA soil survey maps Vitrandic Argixerolls at the center of ZIP 97842: gravelly ashy silt loam, well drained, pH about 6.5 (neutral).

Did spring come early in Imnaha, OR in 2026?

Spring leaf-out near 97842 came on Mar 21 in 2026, 24 days earlier than the 1991–2020 average (Apr 14), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Imnaha, OR?

Long-day onions: the longest day near 97842 is 15 h 42 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).