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

Planting zone for 97123 — Hillsboro, OR

ZIP code 97123 (Hillsboro, Washington County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is April 16 and the first fall frost October 23.

Where ZIP 97123 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 16
First frostOct 23
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 Hillsboro, 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 Hillsboro, OR

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 16median — 50% chance of a later frost
Safe for tender plantsMay 3only 10% chance of frost after
First fall frostOctober 23median — 10% chance by Oct 3
Growing season191 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 13 and returns around November 12.

From the NOAA station Portland-Hillsboro Airport, OR — 7 miles away, elevation 203 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 97123

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 5 – Mar 19
SpinachSow outdoors · Mar 5 – Mar 26
Broccoli, cabbageStart indoors · Feb 5 – Feb 19
Broccoli, cabbageTransplant · Mar 26 – Apr 9
Onion setsPlant outdoors · Mar 19 – Apr 2
PotatoesPlant outdoors · Mar 26 – Apr 9
LettuceSow outdoors · Mar 19 – Apr 2
Carrots, beetsSow outdoors · Mar 26 – Apr 9
TomatoesStart indoors · Feb 19 – Mar 5
TomatoesTransplant · Apr 23 – May 7
Peppers, eggplantStart indoors · Feb 5 – Feb 19
Peppers, eggplantTransplant · Apr 30 – May 14
BeansSow outdoors · Apr 23 – May 7
Sweet cornSow outdoors · Apr 23 – May 7
Cucumbers, squashSow outdoors · Apr 23 – May 7
Fall lettuce, spinachSow outdoors · Aug 28 – Sep 11
GarlicPlant cloves · Oct 9 – Nov 13
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 16) and first fall frost (Oct 23) 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 97123 came on Feb 20 — about the same time as the 1991–2020 average (Feb 18).

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 Hillsboro, OR.

Soil in Hillsboro, OR

The soil mapped at the center of ZIP 97123 is Aloha — silt loam, somewhat poorly drained.

TextureSilt loama good balance for most vegetables
pH5.8moderately acidic; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter2.5%moderate
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classPrime farmland if drainedUSDA classification

Map unit: Aloha 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 97123; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Hillsboro, OR

Summer high82 °Faverage high, July
Winter low33 °Faverage low, December
Hot days17days a year at 90 °F or more
Freezing nights64nights a year at 32 °F or less
Growing degree days2,195base 50 °F — the season’s usable heat
Longest day15 h 41 mindaylight on June 21
Shortest day8 h 42 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation42.5 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 39 °F 61°39° AprMay: average high 69 °F, low 45 °F 69°45° MayJune: average high 74 °F, low 49 °F 74°49° JunJuly: average high 82 °F, low 52 °F 82°52° JulAugust: average high 82 °F, low 52 °F 82°52° AugSeptember: average high 76 °F, low 48 °F 76°48° SepOctober: average high 64 °F, low 41 °F 64°41° OctNovember: average high 53 °F, low 37 °F 53°37° NovDecember: average high 46 °F, low 33 °F 46°33° Dec

Precipitation by month inches

0″2″4″6″8″January: 6.00 in precipitation 6.0 JanFebruary: 5.53 in precipitation 5.5 FebMarch: 4.37 in precipitation 4.4 MarApril: 3.01 in precipitation 3.0 AprMay: 2.21 in precipitation 2.2 MayJune: 1.46 in precipitation 1.5 JunJuly: 0.47 in precipitation 0.5 JulAugust: 0.63 in precipitation 0.6 AugSeptember: 1.51 in precipitation 1.5 SepOctober: 3.66 in precipitation 3.7 OctNovember: 6.46 in precipitation 6.5 NovDecember: 7.18 in precipitation 7.2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Portland-Hillsboro Airport, OR (7 mi away); precipitation: Cornelius 5.1 Sse, OR (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

970788b
Beaverton, OR · 5 mi
970078b
Beaverton, OR · 5 mi
971138b
Cornelius, OR · 5 mi
971298b
Hillsboro, OR · 7 mi
970039a
Beaverton, OR · 7 mi
970068b
Beaverton, OR · 8 mi
971408b
Sherwood, OR · 8 mi
971328b
Newberg, OR · 8 mi

All 3 ZIP codes in Hillsboro → · Oregon planting zones →

Questions about 97123

What planting zone is ZIP code 97123?

ZIP code 97123 (Hillsboro, 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 Hillsboro, OR?

The median last spring frost (32 °F) near 97123 is April 16; after May 3 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Portland-Hillsboro Airport station.

When is the first frost in Hillsboro, OR?

The median first fall frost near 97123 is October 23, giving a median frost-free growing season of 191 days.

When should I plant tomatoes in 97123?

Start tomato seeds indoors around Feb 19 – Mar 5 and set transplants outside around Apr 23 – May 7, one to three weeks after the median last frost.

How much rain and snow does 97123 get?

About 42.5 inches of precipitation a year (NOAA 1991–2020 normals, Cornelius 5.1 Sse station).

How hot do summers get in Hillsboro, OR?

The average high peaks at 82 °F in July, with about 17 days a year at 90 °F or more.

What kind of soil does 97123 have?

The USDA soil survey maps Aloha at the center of ZIP 97123: silt loam, somewhat poorly drained, pH about 5.8 (moderately acidic).

Did spring come early in Hillsboro, OR in 2026?

Spring leaf-out near 97123 came on Feb 20 in 2026, about the same as the 1991–2020 average (Feb 18), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Hillsboro, OR?

Long-day onions: the longest day near 97123 is 15 h 41 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).