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

Planting zone for 98129 — Seattle, WA

ZIP code 98129 (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 98129 is

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 — 6 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 98129

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 98129 came on Feb 5 — 10 days earlier than the 1991–2020 average (Feb 15).

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.

Trees 32

Alaska cedar75 ft · blooms mid spring · low shade tolerance · to −22 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °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 °F

Shrubs 115

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °FBarclay's willow15 ft · high shade tolerance · to −43 °F

Wildflowers & perennials 293

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 159

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 3

riverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °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 Seattle, WA.

Soil in Seattle, WA

The soil mapped at the center of ZIP 98129 is Anthraltic Xerorthents — 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 matter1%low — add compost
Hydrologic groupA/Ddrains fast once dried out; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Urban land, 5 to 20 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 98129; 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 25 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation38.5 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°32 °FJanuary: average high 49 °F, low 37 °F 49°37° JanFebruary: average high 51 °F, low 37 °F 51°37° FebMarch: average high 55 °F, low 39 °F 55°39° MarApril: average high 60 °F, low 44 °F 60°44° AprMay: average high 67 °F, low 49 °F 67°49° MayJune: average high 71 °F, low 54 °F 71°54° JunJuly: average high 77 °F, low 58 °F 77°58° JulAugust: average high 77 °F, low 58 °F 77°58° AugSeptember: average high 72 °F, low 54 °F 72°54° SepOctober: average high 61 °F, low 46 °F 61°46° OctNovember: average high 53 °F, low 40 °F 53°40° NovDecember: average high 48 °F, low 36 °F 48°36° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 5.57 in precipitation 5.6 JanFebruary: 3.67 in precipitation 3.7 FebMarch: 3.79 in precipitation 3.8 MarApril: 3.04 in precipitation 3.0 AprMay: 2.17 in precipitation 2.2 MayJune: 1.65 in precipitation 1.6 JunJuly: 0.76 in precipitation 0.8 JulAugust: 1.05 in precipitation 1.1 AugSeptember: 1.76 in precipitation 1.8 SepOctober: 3.60 in precipitation 3.6 OctNovember: 5.92 in precipitation 5.9 NovDecember: 5.47 in precipitation 5.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Seattle Boeing Field, WA (6 mi away); precipitation: Mercer Island 1.5 Nw, WA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9a.

981119a
Seattle, WA · <1 mi
981149a
Seattle, WA · <1 mi
981249a
Seattle, WA · <1 mi
981319a
Seattle, WA · <1 mi
981389a
Seattle, WA · <1 mi
981459a
Seattle, WA · <1 mi
981609a
Seattle, WA · <1 mi
981619a
Seattle, WA · <1 mi

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

Questions about 98129

What planting zone is ZIP code 98129?

ZIP code 98129 (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 98129 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 98129 is November 17, giving a median frost-free growing season of 247 days.

When should I plant tomatoes in 98129?

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 98129 get?

About 38.5 inches of precipitation a year (NOAA 1991–2020 normals, Mercer Island 1.5 Nw 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 98129 have?

The USDA soil survey maps Anthraltic Xerorthents at the center of ZIP 98129: 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 98129 came on Feb 5 in 2026, 10 days earlier than the 1991–2020 average (Feb 15), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Seattle, WA?

Long-day onions: the longest day near 98129 is 15 h 59 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 98129 change?

Yes. The 2012 USDA map put 98129 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.