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

Planting zone for 98055 — Renton, WA

ZIP code 98055 (Renton, King County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is March 20 and the first fall frost November 10.

Where ZIP 98055 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 20

First frostNov 10

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 Renton, 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 Renton, WA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMarch 20median — 50% chance of a later frost

Safe for tender plantsApril 8only 10% chance of frost after

First fall frostNovember 10median — 10% chance by Oct 26

Growing season233 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 25 and returns around November 24.

From the NOAA station Kent, WA — 3 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 98055

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 6 – Feb 20

SpinachSow outdoors · Feb 6 – Feb 27

Broccoli, cabbageStart indoors · Jan 9 – Jan 23

Broccoli, cabbageTransplant · Feb 27 – Mar 13

Onion setsPlant outdoors · Feb 20 – Mar 6

PotatoesPlant outdoors · Feb 27 – Mar 13

LettuceSow outdoors · Feb 20 – Mar 6

Carrots, beetsSow outdoors · Feb 27 – Mar 13

TomatoesStart indoors · Jan 23 – Feb 6

TomatoesTransplant · Mar 27 – Apr 10

Peppers, eggplantStart indoors · Jan 9 – Jan 23

Peppers, eggplantTransplant · Apr 3 – Apr 17

BeansSow outdoors · Mar 27 – Apr 10

Sweet cornSow outdoors · Mar 27 – Apr 10

Cucumbers, squashSow outdoors · Mar 27 – Apr 10

Fall lettuce, spinachSow outdoors · Sep 15 – Sep 29

GarlicPlant cloves · Oct 27 – Dec 1

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 20) and first fall frost (Nov 10) 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 98055 came on Feb 12 — 4 days earlier than the 1991–2020 average (Feb 16).

average
Feb 162026
Feb 12

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 9a in Washington

617 plants native to the lower 48 states, recorded in Washington, and rated by the USDA to survive 20 °F or colder — the bottom of zone 9a. 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 Renton, WA.

Soil in Renton, WA

The soil mapped at the center of ZIP 98055 is Alderwood — gravelly sandy loam, moderately well drained.

TextureGravelly sandy loamdrains and warms fast; dries out and needs more feeding

pH5.8moderately acidic; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter9%high

Hydrologic groupBwater soaks in moderately

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Alderwood gravelly sandy loam, 8 to 15 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 98055; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Renton, WA

Summer high78 °Faverage high, July

Winter low35 °Faverage low, December

Hot days4days a year at 90 °F or more

Freezing nights39nights a year at 32 °F or less

Growing degree days2,408base 50 °F — the season’s usable heat

Longest day15 h 58 mindaylight on June 21

Shortest day8 h 27 mindaylight on December 21

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

Precipitation43.2 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: Kent, WA (3 mi away); precipitation: Renton 3.6 Sse, WA (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

All 5 ZIP codes in Renton → · Washington planting zones →

Questions about 98055

What planting zone is ZIP code 98055?

ZIP code 98055 (Renton, WA) 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 Renton, WA?

The median last spring frost (32 °F) near 98055 is March 20; after April 8 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Kent station.

When is the first frost in Renton, WA?

The median first fall frost near 98055 is November 10, giving a median frost-free growing season of 233 days.

When should I plant tomatoes in 98055?

Start tomato seeds indoors around Jan 23 – Feb 6 and set transplants outside around Mar 27 – Apr 10, one to three weeks after the median last frost.

How much rain and snow does 98055 get?

About 43.2 inches of precipitation a year (NOAA 1991–2020 normals, Renton 3.6 Sse station).

How hot do summers get in Renton, WA?

The average high peaks at 78 °F in July, with about 4 days a year at 90 °F or more.

What kind of soil does 98055 have?

The USDA soil survey maps Alderwood at the center of ZIP 98055: gravelly sandy loam, moderately well drained, pH about 5.8 (moderately acidic).

Did spring come early in Renton, WA in 2026?

Spring leaf-out near 98055 came on Feb 12 in 2026, 4 days earlier than the 1991–2020 average (Feb 16), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Renton, WA?

Long-day onions: the longest day near 98055 is 15 h 58 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 98055 change?

Yes. The 2012 USDA map put 98055 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.