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

Planting zone for 98136 — Seattle, WA

ZIP code 98136 (Seattle, King County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is March 13 and the first fall frost November 17.

Where ZIP 98136 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 13

First frostNov 17

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 Seattle, 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 Seattle, WA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMarch 13median — 50% chance of a later frost

Safe for tender plantsApril 1only 10% chance of frost after

First fall frostNovember 17median — 10% chance by Nov 1

Growing season247 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 18 and returns around December 2.

From the NOAA station Seattle Boeing Field, WA — 4 miles away, elevation 20 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 98136

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Jan 30 – Feb 13

SpinachSow outdoors · Jan 30 – Feb 20

Broccoli, cabbageStart indoors · Jan 2 – Jan 16

Broccoli, cabbageTransplant · Feb 20 – Mar 6

Onion setsPlant outdoors · Feb 13 – Feb 27

PotatoesPlant outdoors · Feb 20 – Mar 6

LettuceSow outdoors · Feb 13 – Feb 27

Carrots, beetsSow outdoors · Feb 20 – Mar 6

TomatoesStart indoors · Jan 16 – Jan 30

TomatoesTransplant · Mar 20 – Apr 3

Peppers, eggplantStart indoors · Jan 2 – Jan 16

Peppers, eggplantTransplant · Mar 27 – Apr 10

BeansSow outdoors · Mar 20 – Apr 3

Sweet cornSow outdoors · Mar 20 – Apr 3

Cucumbers, squashSow outdoors · Mar 20 – Apr 3

Fall lettuce, spinachSow outdoors · Sep 22 – Oct 6

GarlicPlant cloves · Nov 3 – Dec 8

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 13) and first fall frost (Nov 17) 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 98136 came on Feb 5 — 11 days earlier than the 1991–2020 average (Feb 16).

average
Feb 162026
Feb 5

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 Seattle, WA

The soil mapped at the center of ZIP 98136 is Alderwood — gravelly sandy loam, moderately well drained. Much of the area is built over (urban land); this is the natural soil underneath.

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 groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Urban land-Alderwood complex, 0 to 5 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 98136; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Seattle, WA

Summer high77 °Faverage high, July

Winter low36 °Faverage low, December

Hot days3days a year at 90 °F or more

Freezing nights30nights a year at 32 °F or less

Growing degree days2,392base 50 °F — the season’s usable heat

Longest day15 h 59 mindaylight on June 21

Shortest day8 h 26 mindaylight on December 21

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

Precipitation36.5 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: Seattle Boeing Field, WA (4 mi away); precipitation: Seattle Boeing Field, WA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9a.

Manchester, WA · 5 mi

980629a

Seahurst, WA · 5 mi

All 59 ZIP codes in Seattle → · Washington planting zones →

Questions about 98136

What planting zone is ZIP code 98136?

ZIP code 98136 (Seattle, 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 Seattle, WA?

The median last spring frost (32 °F) near 98136 is March 13; after April 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Seattle Boeing Field station.

When is the first frost in Seattle, WA?

The median first fall frost near 98136 is November 17, giving a median frost-free growing season of 247 days.

When should I plant tomatoes in 98136?

Start tomato seeds indoors around Jan 16 – Jan 30 and set transplants outside around Mar 20 – Apr 3, one to three weeks after the median last frost.

How much rain and snow does 98136 get?

About 36.5 inches of precipitation a year (NOAA 1991–2020 normals, Seattle Boeing Field station).

How hot do summers get in Seattle, WA?

The average high peaks at 77 °F in July, with about 3 days a year at 90 °F or more.

What kind of soil does 98136 have?

The USDA soil survey maps Alderwood at the center of ZIP 98136: gravelly sandy loam, moderately well drained, pH about 5.8 (moderately acidic).

Did spring come early in Seattle, WA in 2026?

Spring leaf-out near 98136 came on Feb 5 in 2026, 11 days earlier than the 1991–2020 average (Feb 16), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Seattle, WA?

Long-day onions: the longest day near 98136 is 15 h 59 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 98136 change?

Yes. The 2012 USDA map put 98136 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.