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

Planting zone for 97865 — Mount Vernon, OR

ZIP code 97865 (Mount Vernon, Grant County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is May 28 and the first fall frost September 18.

Where ZIP 97865 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 28
First frostSep 18
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 Mount Vernon, 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 Mount Vernon, OR

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 28median — 50% chance of a later frost
Safe for tender plantsJune 15only 10% chance of frost after
First fall frostSeptember 18median — 10% chance by Sep 2
Growing season113 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 8 and returns around October 1.

From the NOAA station John Day, OR — 11 miles away, elevation 3,064 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 97865

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 16 – Apr 30
SpinachSow outdoors · Apr 16 – May 7
Broccoli, cabbageStart indoors · Mar 19 – Apr 2
Broccoli, cabbageTransplant · May 7 – May 21
Onion setsPlant outdoors · Apr 30 – May 14
PotatoesPlant outdoors · May 7 – May 21
LettuceSow outdoors · Apr 30 – May 14
Carrots, beetsSow outdoors · May 7 – May 21
TomatoesStart indoors · Apr 2 – Apr 16
TomatoesTransplant · Jun 4 – Jun 18
Peppers, eggplantStart indoors · Mar 19 – Apr 2
Peppers, eggplantTransplant · Jun 11 – Jun 25
BeansSow outdoors · Jun 4 – Jun 18
Sweet cornSow outdoors · Jun 4 – Jun 18
Cucumbers, squashSow outdoors · Jun 4 – Jun 18
Fall lettuce, spinachSow outdoors · Jul 24 – Aug 7
GarlicPlant cloves · Sep 4 – Oct 9
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 28) and first fall frost (Sep 18) 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 97865 came on Mar 10 — 20 days earlier than the 1991–2020 average (Mar 30).

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.

Trees 40

Alaska cedar75 ft · blooms mid spring · low shade tolerance · to −22 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fbigleaf maple60 ft · blooms mid spring · medium shade tolerance · to −14 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fboxelder60 ft · blooms early spring · low shade tolerance · to −46 °FBrewer spruce100 ft · blooms early summer · low shade tolerance · to −13 °F

Shrubs 114

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 °Fbeaked hazelnut15 ft · blooms early spring · low shade tolerance · to −47 °Fbig sagebrush4 ft · blooms mid summer · high shade tolerance · to −43 °F

Wildflowers & perennials 287

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 161

Alaska brome5 ft · blooms late spring · low shade tolerance · to −18 °FAlaska 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 timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °FAmerican beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °F

Vines 2

riverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fwestern 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 Mount Vernon, OR.

Soil in Mount Vernon, OR

The soil mapped at the center of ZIP 97865 is Gwin — cobbly silt loam, well drained.

TextureCobbly silt loama good balance for most vegetables
pH6.6neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Gwin-Rockly-Rock outcrop complex, 20 to 50 percent south 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 97865; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Mount Vernon, OR

Summer high86 °Faverage high, July
Winter low21 °Faverage low, January
Hot days39days a year at 90 °F or more
Freezing nights163nights a year at 32 °F or less
Growing degree days1,760base 50 °F — the season’s usable heat
Longest day15 h 33 mindaylight on June 21
Shortest day8 h 50 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation12.3 inper year, rain and melted snow
Snowfall10 inper year

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 40 °F, low 21 °F 40°21° JanFebruary: average high 45 °F, low 23 °F 45°23° FebMarch: average high 52 °F, low 26 °F 52°26° MarApril: average high 57 °F, low 30 °F 57°30° AprMay: average high 66 °F, low 37 °F 66°37° MayJune: average high 75 °F, low 43 °F 75°43° JunJuly: average high 86 °F, low 48 °F 86°48° JulAugust: average high 86 °F, low 46 °F 86°46° AugSeptember: average high 77 °F, low 39 °F 77°39° SepOctober: average high 62 °F, low 31 °F 62°31° OctNovember: average high 48 °F, low 26 °F 48°26° NovDecember: average high 39 °F, low 21 °F 39°21° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″January: 1.09 in precipitation, 3.5 in snowfall 1.1❄4 JanFebruary: 0.60 in precipitation, 1.4 in snowfall 0.6❄1 FebMarch: 1.14 in precipitation, 1.2 in snowfall 1.1❄1 MarApril: 1.49 in precipitation, 0.3 in snowfall 1.5 AprMay: 1.83 in precipitation 1.8 MayJune: 1.30 in precipitation 1.3 JunJuly: 0.43 in precipitation 0.4 JulAugust: 0.50 in precipitation 0.5 AugSeptember: 0.52 in precipitation 0.5 SepOctober: 1.04 in precipitation, 0.2 in snowfall 1.0 OctNovember: 1.19 in precipitation, 1 in snowfall 1.2❄1 NovDecember: 1.14 in precipitation, 2 in snowfall 1.1❄2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: John Day, OR (11 mi away); precipitation: John Day, OR (11 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.

978456b
John Day, OR · 14 mi
978257a
Dayville, OR · 16 mi
978206b
Canyon City, OR · 22 mi
978566b
Long Creek, OR · 22 mi
978735b
Seneca, OR · 25 mi
978487a
Kimberly, OR · 27 mi
978696b
Prairie City, OR · 27 mi
978647a
Monument, OR · 28 mi

Oregon planting zones →

Questions about 97865

What planting zone is ZIP code 97865?

ZIP code 97865 (Mount Vernon, 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 Mount Vernon, OR?

The median last spring frost (32 °F) near 97865 is May 28; after June 15 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, John Day station.

When is the first frost in Mount Vernon, OR?

The median first fall frost near 97865 is September 18, giving a median frost-free growing season of 113 days.

When should I plant tomatoes in 97865?

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

How much rain and snow does 97865 get?

About 12.3 inches of precipitation a year and 10 inches of snowfall (NOAA 1991–2020 normals, John Day station).

How hot do summers get in Mount Vernon, OR?

The average high peaks at 86 °F in July, with about 39 days a year at 90 °F or more.

What kind of soil does 97865 have?

The USDA soil survey maps Gwin at the center of ZIP 97865: cobbly silt loam, well drained, pH about 6.6 (neutral).

Did spring come early in Mount Vernon, OR in 2026?

Spring leaf-out near 97865 came on Mar 10 in 2026, 20 days earlier than the 1991–2020 average (Mar 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Mount Vernon, OR?

Long-day onions: the longest day near 97865 is 15 h 33 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).