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

Planting zone for 98238 — Conway, WA

ZIP code 98238 (Conway, Skagit County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is March 24 and the first fall frost November 3.

Where ZIP 98238 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 frostMar 24

First frostNov 3

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 Conway, WA…

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 Conway, WA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMarch 24median — 50% chance of a later frost

Safe for tender plantsApril 14only 10% chance of frost after

First fall frostNovember 3median — 10% chance by Oct 12

Growing season224 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 27 and returns around November 25.

From the NOAA station Mt Vernon 3 Wnw, WA — 7 miles away, elevation 13 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 98238

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 10 – Feb 24

SpinachSow outdoors · Feb 10 – Mar 3

Broccoli, cabbageStart indoors · Jan 13 – Jan 27

Broccoli, cabbageTransplant · Mar 3 – Mar 17

Onion setsPlant outdoors · Feb 24 – Mar 10

PotatoesPlant outdoors · Mar 3 – Mar 17

LettuceSow outdoors · Feb 24 – Mar 10

Carrots, beetsSow outdoors · Mar 3 – Mar 17

TomatoesStart indoors · Jan 27 – Feb 10

TomatoesTransplant · Mar 31 – Apr 14

Peppers, eggplantStart indoors · Jan 13 – Jan 27

Peppers, eggplantTransplant · Apr 7 – Apr 21

BeansSow outdoors · Mar 31 – Apr 14

Sweet cornSow outdoors · Mar 31 – Apr 14

Cucumbers, squashSow outdoors · Mar 31 – Apr 14

Fall lettuce, spinachSow outdoors · Sep 8 – Sep 22

GarlicPlant cloves · Oct 20 – Nov 24

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 24) and first fall frost (Nov 3) 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 98238 came on Feb 16 — 6 days earlier than the 1991–2020 average (Feb 22).

average
Feb 222026
Feb 16

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 Washington

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

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 Conway, WA.

Soil in Conway, WA

The soil mapped at the center of ZIP 98238 is Skagit — silt loam, poorly drained.

TextureSilt loama good balance for most vegetables

pH6.5neutral; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter4%moderate

Hydrologic groupB/Dmoderate when drained; wet otherwise

Farmland classPrime farmland if drainedUSDA classification

Map unit: Skagit 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 98238; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Conway, WA

Summer high75 °Faverage high, August

Winter low35 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights46nights a year at 32 °F or less

Growing degree days1,764base 50 °F — the season’s usable heat

Longest day16 h 06 mindaylight on June 21

Shortest day8 h 19 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation34.6 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: Mt Vernon 3 Wnw, WA (7 mi away); precipitation: Stanwood 0.7 N, WA (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 8b.

982738b

Mount Vernon, WA · 5 mi

Mount Vernon, WA · 9 mi

982878b

Silvana, WA · 10 mi

982358b

Clearlake, WA · 10 mi

982828b

Camano Island, WA · 11 mi

982338b

Burlington, WA · 11 mi

Washington planting zones →

Questions about 98238

What planting zone is ZIP code 98238?

ZIP code 98238 (Conway, WA) 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 Conway, WA?

The median last spring frost (32 °F) near 98238 is March 24; after April 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Mt Vernon 3 Wnw station.

When is the first frost in Conway, WA?

The median first fall frost near 98238 is November 3, giving a median frost-free growing season of 224 days.

When should I plant tomatoes in 98238?

Start tomato seeds indoors around Jan 27 – Feb 10 and set transplants outside around Mar 31 – Apr 14, one to three weeks after the median last frost.

How much rain and snow does 98238 get?

About 34.6 inches of precipitation a year (NOAA 1991–2020 normals, Stanwood 0.7 N station).

How hot do summers get in Conway, WA?

The average high peaks at 75 °F in August, with about 0 days a year at 90 °F or more.

What kind of soil does 98238 have?

The USDA soil survey maps Skagit at the center of ZIP 98238: silt loam, poorly drained, pH about 6.5 (neutral).

Did spring come early in Conway, WA in 2026?

Spring leaf-out near 98238 came on Feb 16 in 2026, 6 days earlier than the 1991–2020 average (Feb 22), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Conway, WA?

Long-day onions: the longest day near 98238 is 16 h 06 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).