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

Planting zone for 97133 — North Plains, OR

ZIP code 97133 (North Plains, Washington County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is April 10 and the first fall frost November 2.

Where ZIP 97133 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 10
First frostNov 2
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 North Plains, 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 North Plains, OR

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 10median — 50% chance of a later frost
Safe for tender plantsMay 1only 10% chance of frost after
First fall frostNovember 2median — 10% chance by Oct 16
Growing season209 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 3 and returns around November 19.

From the NOAA station Scappoose Ind Airport, OR — 9 miles away, elevation 56 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 97133

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 27 – Mar 13
SpinachSow outdoors · Feb 27 – Mar 20
Broccoli, cabbageStart indoors · Jan 30 – Feb 13
Broccoli, cabbageTransplant · Mar 20 – Apr 3
Onion setsPlant outdoors · Mar 13 – Mar 27
PotatoesPlant outdoors · Mar 20 – Apr 3
LettuceSow outdoors · Mar 13 – Mar 27
Carrots, beetsSow outdoors · Mar 20 – Apr 3
TomatoesStart indoors · Feb 13 – Feb 27
TomatoesTransplant · Apr 17 – May 1
Peppers, eggplantStart indoors · Jan 30 – Feb 13
Peppers, eggplantTransplant · Apr 24 – May 8
BeansSow outdoors · Apr 17 – May 1
Sweet cornSow outdoors · Apr 17 – May 1
Cucumbers, squashSow outdoors · Apr 17 – May 1
Fall lettuce, spinachSow outdoors · Sep 7 – Sep 21
GarlicPlant cloves · Oct 19 – Nov 23
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 10) and first fall frost (Nov 2) 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 97133 came on Mar 5 — 8 days earlier than the 1991–2020 average (Mar 13).

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).

Soil in North Plains, OR

The soil mapped at the center of ZIP 97133 is Laurelwood — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH5.8moderately acidic; 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: Laurelwood silt loam, 20 to 30 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 97133; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in North Plains, OR

Summer high82 °Faverage high, August
Winter low34 °Faverage low, January
Hot days14days a year at 90 °F or more
Freezing nights61nights a year at 32 °F or less
Growing degree days2,345base 50 °F — the season’s usable heat
Longest day15 h 43 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)
Precipitation42.3 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°32 °FJanuary: average high 47 °F, low 34 °F 47°34° JanFebruary: average high 51 °F, low 34 °F 51°34° FebMarch: average high 56 °F, low 37 °F 56°37° MarApril: average high 61 °F, low 40 °F 61°40° AprMay: average high 68 °F, low 46 °F 68°46° MayJune: average high 73 °F, low 51 °F 73°51° JunJuly: average high 81 °F, low 55 °F 81°55° JulAugust: average high 82 °F, low 54 °F 82°54° AugSeptember: average high 76 °F, low 50 °F 76°50° SepOctober: average high 64 °F, low 43 °F 64°43° OctNovember: average high 53 °F, low 37 °F 53°37° NovDecember: average high 46 °F, low 34 °F 46°34° Dec

Precipitation by month inches

0″2″4″6″8″January: 6.54 in precipitation 6.5 JanFebruary: 4.62 in precipitation 4.6 FebMarch: 4.54 in precipitation 4.5 MarApril: 3.08 in precipitation 3.1 AprMay: 2.49 in precipitation 2.5 MayJune: 1.37 in precipitation 1.4 JunJuly: 0.48 in precipitation 0.5 JulAugust: 0.52 in precipitation 0.5 AugSeptember: 1.56 in precipitation 1.6 SepOctober: 3.60 in precipitation 3.6 OctNovember: 6.26 in precipitation 6.3 NovDecember: 7.25 in precipitation 7.3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Scappoose Ind Airport, OR (9 mi away); precipitation: Scappoose Ind Airport, OR (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 8b.

971068b
Banks, OR · 6 mi
970568b
Scappoose, OR · 8 mi
971248b
Hillsboro, OR · 9 mi
972318b
Portland, OR · 9 mi
971098b
Buxton, OR · 9 mi
971258b
Manning, OR · 10 mi
971168b
Forest Grove, OR · 11 mi
971298b
Hillsboro, OR · 11 mi

Oregon planting zones →

Questions about 97133

What planting zone is ZIP code 97133?

ZIP code 97133 (North Plains, 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 North Plains, OR?

The median last spring frost (32 °F) near 97133 is April 10; after May 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Scappoose Ind Airport station.

When is the first frost in North Plains, OR?

The median first fall frost near 97133 is November 2, giving a median frost-free growing season of 209 days.

When should I plant tomatoes in 97133?

Start tomato seeds indoors around Feb 13 – Feb 27 and set transplants outside around Apr 17 – May 1, one to three weeks after the median last frost.

How much rain and snow does 97133 get?

About 42.3 inches of precipitation a year (NOAA 1991–2020 normals, Scappoose Ind Airport station).

How hot do summers get in North Plains, OR?

The average high peaks at 82 °F in August, with about 14 days a year at 90 °F or more.

What kind of soil does 97133 have?

The USDA soil survey maps Laurelwood at the center of ZIP 97133: silt loam, well drained, pH about 5.8 (moderately acidic).

Did spring come early in North Plains, OR in 2026?

Spring leaf-out near 97133 came on Mar 5 in 2026, 8 days earlier than the 1991–2020 average (Mar 13), according to the USA National Phenology Network Spring Index.

What kind of onions grow in North Plains, OR?

Long-day onions: the longest day near 97133 is 15 h 43 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).