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

Planting zone for 97361 — Monmouth, OR

ZIP code 97361 (Monmouth, Polk County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is April 18 and the first fall frost November 7.

Where ZIP 97361 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.

Zone8b15 to 20 °F
Coldest night−9.4 to −6.7 °C
Last frostApr 18
First frostNov 7
2012 zone8b

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 8b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Monmouth, 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 Monmouth, OR

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 18median — 50% chance of a later frost
Safe for tender plantsMay 6only 10% chance of frost after
First fall frostNovember 7median — 10% chance by Oct 21
Growing season202 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 13 and returns around November 23.

From the NOAA station Falls City 2 Ssw, OR — 7 miles away, elevation 689 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 97361

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 7 – Mar 21
SpinachSow outdoors · Mar 7 – Mar 28
Broccoli, cabbageStart indoors · Feb 7 – Feb 21
Broccoli, cabbageTransplant · Mar 28 – Apr 11
Onion setsPlant outdoors · Mar 21 – Apr 4
PotatoesPlant outdoors · Mar 28 – Apr 11
LettuceSow outdoors · Mar 21 – Apr 4
Carrots, beetsSow outdoors · Mar 28 – Apr 11
TomatoesStart indoors · Feb 21 – Mar 7
TomatoesTransplant · Apr 25 – May 9
Peppers, eggplantStart indoors · Feb 7 – Feb 21
Peppers, eggplantTransplant · May 2 – May 16
BeansSow outdoors · Apr 25 – May 9
Sweet cornSow outdoors · Apr 25 – May 9
Cucumbers, squashSow outdoors · Apr 25 – May 9
Fall lettuce, spinachSow outdoors · Sep 12 – Sep 26
GarlicPlant cloves · Oct 24 – Nov 28
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 18) and first fall frost (Nov 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 97361 came on Feb 22 — 3 days later than the 1991–2020 average (Feb 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 8b in Oregon

661 plants native to the lower 48 states, recorded in Oregon, and rated by the USDA to survive 15 °F or colder — the bottom of zone 8b. Each links to its USDA PLANTS profile.

Trees 43

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 132

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 305

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 166

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 Monmouth, OR.

Soil in Monmouth, OR

The soil mapped at the center of ZIP 97361 is Holcomb — silt loam, somewhat poorly drained.

TextureSilt loama good balance for most vegetables
pH6.1slightly acidic; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter4%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classPrime farmland if drainedUSDA classification

Map unit: Holcomb silt loam.

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 97361; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Monmouth, OR

Summer high81 °Faverage high, August
Winter low33 °Faverage low, January
Hot days13days a year at 90 °F or more
Freezing nights70nights a year at 32 °F or less
Growing degree days1,872base 50 °F — the season’s usable heat
Longest day15 h 35 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)
Precipitation45 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°32 °FJanuary: average high 45 °F, low 33 °F 45°33° JanFebruary: average high 49 °F, low 33 °F 49°33° FebMarch: average high 53 °F, low 35 °F 53°35° MarApril: average high 58 °F, low 38 °F 58°38° AprMay: average high 65 °F, low 43 °F 65°43° MayJune: average high 70 °F, low 47 °F 70°47° JunJuly: average high 80 °F, low 50 °F 80°50° JulAugust: average high 81 °F, low 50 °F 81°50° AugSeptember: average high 75 °F, low 48 °F 75°48° SepOctober: average high 62 °F, low 43 °F 62°43° OctNovember: average high 51 °F, low 37 °F 51°37° NovDecember: average high 45 °F, low 33 °F 45°33° Dec

Precipitation by month inches

0″2″4″6″8″January: 6.63 in precipitation 6.6 JanFebruary: 5.14 in precipitation 5.1 FebMarch: 5.09 in precipitation 5.1 MarApril: 3.79 in precipitation 3.8 AprMay: 2.40 in precipitation 2.4 MayJune: 1.30 in precipitation 1.3 JunJuly: 0.39 in precipitation 0.4 JulAugust: 0.45 in precipitation 0.5 AugSeptember: 1.50 in precipitation 1.5 SepOctober: 3.66 in precipitation 3.7 OctNovember: 6.81 in precipitation 6.8 NovDecember: 7.81 in precipitation 7.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Falls City 2 Ssw, OR (7 mi away); precipitation: Monmouth 6.3 S, OR (5 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 8b.

973448b
Falls City, OR · 9 mi
973308b
Corvallis, OR · 10 mi
973518b
Independence, OR · 10 mi
973388b
Dallas, OR · 11 mi
973068b
Salem, OR · 12 mi
973218b
Albany, OR · 13 mi
973528b
Jefferson, OR · 15 mi
973318b
Corvallis, OR · 15 mi

Oregon planting zones →

Questions about 97361

What planting zone is ZIP code 97361?

ZIP code 97361 (Monmouth, OR) is in USDA hardiness zone 8b on the 2023 map: the coldest night of an average winter reaches 15 to 20 °F (−9.4 to −6.7 °C).

When is the last frost in Monmouth, OR?

The median last spring frost (32 °F) near 97361 is April 18; after May 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Falls City 2 Ssw station.

When is the first frost in Monmouth, OR?

The median first fall frost near 97361 is November 7, giving a median frost-free growing season of 202 days.

When should I plant tomatoes in 97361?

Start tomato seeds indoors around Feb 21 – Mar 7 and set transplants outside around Apr 25 – May 9, one to three weeks after the median last frost.

How much rain and snow does 97361 get?

About 45 inches of precipitation a year (NOAA 1991–2020 normals, Monmouth 6.3 S station).

How hot do summers get in Monmouth, OR?

The average high peaks at 81 °F in August, with about 13 days a year at 90 °F or more.

What kind of soil does 97361 have?

The USDA soil survey maps Holcomb at the center of ZIP 97361: silt loam, somewhat poorly drained, pH about 6.1 (slightly acidic).

Did spring come early in Monmouth, OR in 2026?

Spring leaf-out near 97361 came on Feb 22 in 2026, 3 days later than the 1991–2020 average (Feb 19), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Monmouth, OR?

Long-day onions: the longest day near 97361 is 15 h 35 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).