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

Planting zone for 97838 — Hermiston, OR

ZIP code 97838 (Hermiston, Umatilla County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 27 and the first fall frost October 7.

Where ZIP 97838 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.

Zone7b5 to 10 °F

Coldest night−15 to −12.2 °C

Last frostApr 27

First frostOct 7

2012 zone7a

Was 7a 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 7b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Hermiston, 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 Hermiston, OR

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 27median — 50% chance of a later frost

Safe for tender plantsMay 11only 10% chance of frost after

First fall frostOctober 7median — 10% chance by Sep 25

Growing season163 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 10 and returns around October 20.

From the NOAA station Hermiston 2 Nw, OR — within 1 mile, elevation 459 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 97838

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 16 – Mar 30

SpinachSow outdoors · Mar 16 – Apr 6

Broccoli, cabbageStart indoors · Feb 16 – Mar 2

Broccoli, cabbageTransplant · Apr 6 – Apr 20

Onion setsPlant outdoors · Mar 30 – Apr 13

PotatoesPlant outdoors · Apr 6 – Apr 20

LettuceSow outdoors · Mar 30 – Apr 13

Carrots, beetsSow outdoors · Apr 6 – Apr 20

TomatoesStart indoors · Mar 2 – Mar 16

TomatoesTransplant · May 4 – May 18

Peppers, eggplantStart indoors · Feb 16 – Mar 2

Peppers, eggplantTransplant · May 11 – May 25

BeansSow outdoors · May 4 – May 18

Sweet cornSow outdoors · May 4 – May 18

Cucumbers, squashSow outdoors · May 4 – May 18

Fall lettuce, spinachSow outdoors · Aug 12 – Aug 26

GarlicPlant cloves · Sep 23 – Oct 28

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 27) and first fall frost (Oct 7) 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 97838 came on Mar 3 — 6 days earlier than the 1991–2020 average (Mar 9).

average
Mar 92026
Mar 3

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 7b in Oregon

627 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 7b. 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 Hermiston, OR.

Soil in Hermiston, OR

The soil mapped at the center of ZIP 97838 is Winchester — sand, excessively drained.

TextureSanddrains and warms fast; dries out and needs more feeding

pH7.3neutral; most vegetables like 6.0–7.0

DrainageExcessively drainednatural drainage class

Organic matter0.75%low — add compost

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Winchester-Urban land complex, 0 to 5 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 97838; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Hermiston, OR

Summer high89 °Faverage high, July

Winter low26 °Faverage low, January

Hot days46days a year at 90 °F or more

Freezing nights122nights a year at 32 °F or less

Growing degree days2,756base 50 °F — the season’s usable heat

Longest day15 h 44 mindaylight on June 21

Shortest day8 h 39 mindaylight on December 21

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

Precipitation8.8 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: Hermiston 2 Nw, OR (within 1 mile); precipitation: Hermiston 2 Nw, OR (within 1 mile). 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.

Kennewick, WA · 17 mi

993457b

Paterson, WA · 19 mi

993387b

Kennewick, WA · 22 mi

Oregon planting zones →

Questions about 97838

What planting zone is ZIP code 97838?

ZIP code 97838 (Hermiston, OR) is in USDA hardiness zone 7b on the 2023 map: the coldest night of an average winter reaches 5 to 10 °F (−15 to −12.2 °C).

When is the last frost in Hermiston, OR?

The median last spring frost (32 °F) near 97838 is April 27; after May 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Hermiston 2 Nw station.

When is the first frost in Hermiston, OR?

The median first fall frost near 97838 is October 7, giving a median frost-free growing season of 163 days.

When should I plant tomatoes in 97838?

Start tomato seeds indoors around Mar 2 – Mar 16 and set transplants outside around May 4 – May 18, one to three weeks after the median last frost.

How much rain and snow does 97838 get?

About 8.8 inches of precipitation a year (NOAA 1991–2020 normals, Hermiston 2 Nw station).

How hot do summers get in Hermiston, OR?

The average high peaks at 89 °F in July, with about 46 days a year at 90 °F or more.

What kind of soil does 97838 have?

The USDA soil survey maps Winchester at the center of ZIP 97838: sand, excessively drained, pH about 7.3 (neutral).

Did spring come early in Hermiston, OR in 2026?

Spring leaf-out near 97838 came on Mar 3 in 2026, 6 days earlier than the 1991–2020 average (Mar 9), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Hermiston, OR?

Long-day onions: the longest day near 97838 is 15 h 44 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 97838 change?

Yes. The 2012 USDA map put 97838 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.