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

Planting zone for Sammamish, WA

Sammamish, WA is in USDA zone 8b across its 2 ZIP codes. The median last spring frost is March 8 and the first fall frost November 23.

Sammamish on the zone map

Outlined: its 2 ZIP code areas · 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
ZIP codes2
Last frostMar 8
First frostNov 23
Growing season259 days

8b 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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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 Sammamish, 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, 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 Sammamish

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 98074 came on Feb 17 — 4 days earlier than the 1991–2020 average (Feb 21).

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.

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 114

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 157

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 Sammamish, WA.

Soil in Sammamish, WA

The soil mapped at the center of ZIP 98074 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 98074; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Sammamish, 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 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)
Precipitation47.4 inper year, rain and melted snow

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

0″2″4″6″8″January: 5.92 in precipitation 5.9 JanFebruary: 4.61 in precipitation 4.6 FebMarch: 5.52 in precipitation 5.5 MarApril: 4.06 in precipitation 4.1 AprMay: 2.46 in precipitation 2.5 MayJune: 2.07 in precipitation 2.1 JunJuly: 0.99 in precipitation 1.0 JulAugust: 1.12 in precipitation 1.1 AugSeptember: 2.01 in precipitation 2.0 SepOctober: 4.41 in precipitation 4.4 OctNovember: 7.40 in precipitation 7.4 NovDecember: 6.87 in precipitation 6.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Seattle Sand Pt Wsfo, WA (11 mi away); precipitation: Issaquah 3.6 Nw, WA (4 mi away). Daylight is calculated from latitude.

ZIP codes in Sammamish

980748b
15 to 20 °F
980758b
15 to 20 °F

Washington planting zones →

Questions about Sammamish

What planting zone is Sammamish, WA?

Sammamish, WA is in USDA hardiness zone 8b on the 2023 map (8b: 15 to 20 °F).

When is the last frost in Sammamish, WA?

The median last spring frost is March 8 and the median first fall frost is November 23 (NOAA 1991–2020 normals, Seattle Sand Pt Wsfo station).

When can I plant a garden in Sammamish, WA?

Cool-season crops like peas and spinach go in around Jan 25 – Feb 15; tomatoes, peppers, beans and squash after about Mar 15, once frost risk has passed.

What kind of onions grow in Sammamish, WA?

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

How much rain and snow does Sammamish, WA get?

About 47.4 inches of precipitation a year (NOAA 1991–2020 normals).