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

Planting zone for 97840 — Oxbow, OR

ZIP code 97840 (Oxbow, Baker County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 2 and the first fall frost November 5.

Where ZIP 97840 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.

Zone7a0 to 5 °F

Coldest night−17.8 to −15 °C

Last frostApr 2

First frostNov 5

2012 zone6a

Was 6a on the 2012 map — a full zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Oxbow, 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 Oxbow, OR

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 2median — 50% chance of a later frost

Safe for tender plantsApril 20only 10% chance of frost after

First fall frostNovember 5median — 10% chance by Oct 24

Growing season216 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 13 and returns around November 16.

From the NOAA station Brownlee Dam, ID — 2 miles away, elevation 1,844 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 97840

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 19 – Mar 5

SpinachSow outdoors · Feb 19 – Mar 12

Broccoli, cabbageStart indoors · Jan 22 – Feb 5

Broccoli, cabbageTransplant · Mar 12 – Mar 26

Onion setsPlant outdoors · Mar 5 – Mar 19

PotatoesPlant outdoors · Mar 12 – Mar 26

LettuceSow outdoors · Mar 5 – Mar 19

Carrots, beetsSow outdoors · Mar 12 – Mar 26

TomatoesStart indoors · Feb 5 – Feb 19

TomatoesTransplant · Apr 9 – Apr 23

Peppers, eggplantStart indoors · Jan 22 – Feb 5

Peppers, eggplantTransplant · Apr 16 – Apr 30

BeansSow outdoors · Apr 9 – Apr 23

Sweet cornSow outdoors · Apr 9 – Apr 23

Cucumbers, squashSow outdoors · Apr 9 – Apr 23

Fall lettuce, spinachSow outdoors · Sep 10 – Sep 24

GarlicPlant cloves · Oct 22 – Nov 26

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 2) and first fall frost (Nov 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 97840 came on Mar 19 — 11 days earlier than the 1991–2020 average (Mar 30).

average
Mar 302026
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 7a in Oregon

624 plants native to the lower 48 states, recorded in Oregon, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. 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 Oxbow, OR.

Soil in Oxbow, OR

The soil mapped at the center of ZIP 97840 is Sag — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH6.7neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3%moderate

Hydrologic groupBwater soaks in moderately

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Sag-Snell complex, 12 to 35 percent north 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 97840; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Oxbow, OR

Summer high95 °Faverage high, July

Winter low28 °Faverage low, January

Hot days68days a year at 90 °F or more

Freezing nights79nights a year at 32 °F or less

Growing degree days3,703base 50 °F — the season’s usable heat

Longest day15 h 36 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)

Precipitation14.8 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: Brownlee Dam, ID (2 mi away); precipitation: Brownlee Dam, ID (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

836107a

Cambridge, ID · 11 mi

Oregon planting zones →

Questions about 97840

What planting zone is ZIP code 97840?

ZIP code 97840 (Oxbow, OR) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Oxbow, OR?

The median last spring frost (32 °F) near 97840 is April 2; after April 20 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Brownlee Dam station.

When is the first frost in Oxbow, OR?

The median first fall frost near 97840 is November 5, giving a median frost-free growing season of 216 days.

When should I plant tomatoes in 97840?

Start tomato seeds indoors around Feb 5 – Feb 19 and set transplants outside around Apr 9 – Apr 23, one to three weeks after the median last frost.

How much rain and snow does 97840 get?

About 14.8 inches of precipitation a year (NOAA 1991–2020 normals, Brownlee Dam station).

How hot do summers get in Oxbow, OR?

The average high peaks at 95 °F in July, with about 68 days a year at 90 °F or more.

What kind of soil does 97840 have?

The USDA soil survey maps Sag at the center of ZIP 97840: silt loam, well drained, pH about 6.7 (neutral).

Did spring come early in Oxbow, OR in 2026?

Spring leaf-out near 97840 came on Mar 19 in 2026, 11 days earlier than the 1991–2020 average (Mar 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Oxbow, OR?

Long-day onions: the longest day near 97840 is 15 h 36 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 97840 change?

Yes. The 2012 USDA map put 97840 in zone 6a; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.