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

Planting zone for 98033 — Kirkland, WA

ZIP code 98033 (Kirkland, King County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is March 8 and the first fall frost November 23.

Where ZIP 98033 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 8
First frostNov 23
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 Kirkland, 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 Kirkland, WA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 8median — 50% chance of a later frost
Safe for tender plantsMarch 29only 10% chance of frost after
First fall frostNovember 23median — 10% chance by Nov 4
Growing season259 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 11 and returns around December 11.

From the NOAA station Seattle Sand Pt Wsfo, WA — 3 miles away, elevation 59 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 98033

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 25 – Feb 8
SpinachSow outdoors · Jan 25 – Feb 15
Broccoli, cabbageStart indoors · Dec 28 – Jan 11
Broccoli, cabbageTransplant · Feb 15 – Mar 1
Onion setsPlant outdoors · Feb 8 – Feb 22
PotatoesPlant outdoors · Feb 15 – Mar 1
LettuceSow outdoors · Feb 8 – Feb 22
Carrots, beetsSow outdoors · Feb 15 – Mar 1
TomatoesStart indoors · Jan 11 – Jan 25
TomatoesTransplant · Mar 15 – Mar 29
Peppers, eggplantStart indoors · Dec 28 – Jan 11
Peppers, eggplantTransplant · Mar 22 – Apr 5
BeansSow outdoors · Mar 15 – Mar 29
Sweet cornSow outdoors · Mar 15 – Mar 29
Cucumbers, squashSow outdoors · Mar 15 – Mar 29
Fall lettuce, spinachSow outdoors · Sep 28 – Oct 12
GarlicPlant cloves · Nov 9 – Dec 14
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 8) and first fall frost (Nov 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 98033 came on Feb 7 — 8 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 Kirkland, WA.

Soil in Kirkland, WA

The soil mapped at the center of ZIP 98033 is Arents — 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 matter1%low — add compost
Hydrologic groupB/Dmoderate when drained; wet otherwise
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Arents, Alderwood material, 6 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 98033; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Kirkland, WA

Summer high77 °Faverage high, July
Winter low37 °Faverage low, January
Hot days2days a year at 90 °F or more
Freezing nights25nights a year at 32 °F or less
Growing degree days2,207base 50 °F — the season’s usable heat
Longest day16 h 00 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)
Precipitation37.8 inper year, rain and melted snow
Snowfall4 inper year; 2 days with snow on the ground

Average high and low, by month

30°40°50°60°70°80°90°32 °FJanuary: average high 47 °F, low 37 °F 47°37° JanFebruary: average high 50 °F, low 37 °F 50°37° FebMarch: average high 54 °F, low 39 °F 54°39° MarApril: average high 59 °F, low 43 °F 59°43° AprMay: average high 65 °F, low 48 °F 65°48° MayJune: average high 70 °F, low 53 °F 70°53° JunJuly: average high 77 °F, low 57 °F 77°57° JulAugust: average high 77 °F, low 57 °F 77°57° AugSeptember: average high 71 °F, low 53 °F 71°53° SepOctober: average high 61 °F, low 47 °F 61°47° OctNovember: average high 52 °F, low 41 °F 52°41° NovDecember: average high 47 °F, low 37 °F 47°37° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 5.14 in precipitation, 0.9 in snowfall 5.1❄1 JanFebruary: 3.54 in precipitation, 1 in snowfall 3.5❄1 FebMarch: 3.86 in precipitation 3.9 MarApril: 2.98 in precipitation 3.0 AprMay: 2.16 in precipitation 2.2 MayJune: 1.57 in precipitation 1.6 JunJuly: 0.78 in precipitation 0.8 JulAugust: 1.00 in precipitation 1.0 AugSeptember: 1.74 in precipitation 1.7 SepOctober: 3.65 in precipitation 3.6 OctNovember: 5.85 in precipitation, 0.2 in snowfall 5.8 NovDecember: 5.55 in precipitation, 1.7 in snowfall 5.5❄2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Seattle Sand Pt Wsfo, WA (3 mi away); precipitation: Seattle Sand Pt Wsfo, WA (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

980838b
Kirkland, WA · <1 mi
980349a
Kirkland, WA · 3 mi
980739a
Redmond, WA · 3 mi
980528b
Redmond, WA · 3 mi
980399a
Medina, WA · 4 mi
980049a
Bellevue, WA · 4 mi
981159a
Seattle, WA · 4 mi
981059a
Seattle, WA · 4 mi

All 3 ZIP codes in Kirkland → · Washington planting zones →

Questions about 98033

What planting zone is ZIP code 98033?

ZIP code 98033 (Kirkland, 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 Kirkland, WA?

The median last spring frost (32 °F) near 98033 is March 8; after March 29 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Seattle Sand Pt Wsfo station.

When is the first frost in Kirkland, WA?

The median first fall frost near 98033 is November 23, giving a median frost-free growing season of 259 days.

When should I plant tomatoes in 98033?

Start tomato seeds indoors around Jan 11 – Jan 25 and set transplants outside around Mar 15 – Mar 29, one to three weeks after the median last frost.

How much rain and snow does 98033 get?

About 37.8 inches of precipitation a year and 4 inches of snowfall (NOAA 1991–2020 normals, Seattle Sand Pt Wsfo station).

How hot do summers get in Kirkland, WA?

The average high peaks at 77 °F in July, with about 2 days a year at 90 °F or more.

What kind of soil does 98033 have?

The USDA soil survey maps Arents at the center of ZIP 98033: gravelly sandy loam, moderately well drained, pH about 5.8 (moderately acidic).

Did spring come early in Kirkland, WA in 2026?

Spring leaf-out near 98033 came on Feb 7 in 2026, 8 days earlier than the 1991–2020 average (Feb 15), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Kirkland, WA?

Long-day onions: the longest day near 98033 is 16 h 00 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 98033 change?

Yes. The 2012 USDA map put 98033 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.