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

Planting zone for 97203 — Portland, OR

ZIP code 97203 (Portland, Multnomah County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is March 29 and the first fall frost November 9.

Where ZIP 97203 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.

Zone9a20 to 25 °F

Coldest night−6.7 to −3.9 °C

Last frostMar 29

First frostNov 9

2012 zone8b

Was 8b 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 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Portland, 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 Portland, OR

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMarch 29median — 50% chance of a later frost

Safe for tender plantsApril 18only 10% chance of frost after

First fall frostNovember 9median — 10% chance by Oct 22

Growing season223 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 3 and returns around November 26.

From the NOAA station Vancouver Pearson Airport, WA — 4 miles away, elevation 30 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 97203

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 15 – Mar 1

SpinachSow outdoors · Feb 15 – Mar 8

Broccoli, cabbageStart indoors · Jan 18 – Feb 1

Broccoli, cabbageTransplant · Mar 8 – Mar 22

Onion setsPlant outdoors · Mar 1 – Mar 15

PotatoesPlant outdoors · Mar 8 – Mar 22

LettuceSow outdoors · Mar 1 – Mar 15

Carrots, beetsSow outdoors · Mar 8 – Mar 22

TomatoesStart indoors · Feb 1 – Feb 15

TomatoesTransplant · Apr 5 – Apr 19

Peppers, eggplantStart indoors · Jan 18 – Feb 1

Peppers, eggplantTransplant · Apr 12 – Apr 26

BeansSow outdoors · Apr 5 – Apr 19

Sweet cornSow outdoors · Apr 5 – Apr 19

Cucumbers, squashSow outdoors · Apr 5 – Apr 19

Fall lettuce, spinachSow outdoors · Sep 14 – Sep 28

GarlicPlant cloves · Oct 26 – Nov 30

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 29) and first fall frost (Nov 9) 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 97203 came on Feb 9 — 9 days earlier than the 1991–2020 average (Feb 18).

average
Feb 182026
Feb 9

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 Portland, OR

The soil mapped at the center of ZIP 97203 is Sauvie — silt loam, poorly drained.

TextureSilt loama good balance for most vegetables

pH6.1slightly acidic; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter3%moderate

Hydrologic groupC/Dslow when drained; wet otherwise

Farmland classPrime farmland if drained and either protected from flooding or not frequently flooded during the growing seasonUSDA classification

Map unit: Sauvie 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 97203; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Portland, OR

Summer high82 °Faverage high, August

Winter low34 °Faverage low, January

Hot days15days a year at 90 °F or more

Freezing nights45nights a year at 32 °F or less

Growing degree days2,573base 50 °F — the season’s usable heat

Longest day15 h 42 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)

Precipitation37.5 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: Vancouver Pearson Airport, WA (4 mi away); precipitation: Vancouver Pearson Airport, WA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

All 59 ZIP codes in Portland → · Oregon planting zones →

Questions about 97203

What planting zone is ZIP code 97203?

ZIP code 97203 (Portland, OR) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in Portland, OR?

The median last spring frost (32 °F) near 97203 is March 29; after April 18 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Vancouver Pearson Airport station.

When is the first frost in Portland, OR?

The median first fall frost near 97203 is November 9, giving a median frost-free growing season of 223 days.

When should I plant tomatoes in 97203?

Start tomato seeds indoors around Feb 1 – Feb 15 and set transplants outside around Apr 5 – Apr 19, one to three weeks after the median last frost.

How much rain and snow does 97203 get?

About 37.5 inches of precipitation a year (NOAA 1991–2020 normals, Vancouver Pearson Airport station).

How hot do summers get in Portland, OR?

The average high peaks at 82 °F in August, with about 15 days a year at 90 °F or more.

What kind of soil does 97203 have?

The USDA soil survey maps Sauvie at the center of ZIP 97203: silt loam, poorly drained, pH about 6.1 (slightly acidic).

Did spring come early in Portland, OR in 2026?

Spring leaf-out near 97203 came on Feb 9 in 2026, 9 days earlier than the 1991–2020 average (Feb 18), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Portland, OR?

Long-day onions: the longest day near 97203 is 15 h 42 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 97203 change?

Yes. The 2012 USDA map put 97203 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.