When is the last frost in Sammamish, WA?

The average last spring frost (50% probability of 32°F) in Sammamish is around March 30, based on NOAA/NCEI 1991–2020 normals at the Snoqualmie Falls, WA station (9.9 mi away). Half of years it falls outside that date, so wait 1–2 weeks past it before setting out frost-tender plants.

When is the first fall frost in Sammamish?

The average first fall frost in Sammamish, WA is around November 7, giving roughly a 223-day frost-free growing season.

What planting zone is Sammamish, WA?

Sammamish is in USDA plant hardiness zone 8b (average annual extreme minimum temperature 15 to 20°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Sammamish?

In Sammamish, WA the warmest month is August (avg high 76.7°F) and the coldest is February (avg low 35.3°F). It averages about 63.3″ of precipitation a year and 3.6″ of snow.

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Sammamish, WA Planting Calendar & Frost Dates

USDA hardiness zone 8b · ZIP 98075 · elevation 134′ · NOAA & USDA data

Sammamish is in USDA hardiness zone 8b (winters can dip to 15 to 20°F), with a growing season of about 223 days between the average last spring frost (March 30) and first fall frost (November 7). The warmest month is August (avg high 76.7°F); the coldest is February (avg low 35.3°F). It averages 63.3″ of precipitation a year and 3.6″ of snow, mostly mid-winter. Start cool-season crops several weeks before the last frost; wait until after it for tomatoes, peppers and other tender crops.

Hardiness zone

min temp 15 to 20°F

Last spring frost

March 30

avg (50% prob, 32°F)

First fall frost

November 7

avg (50% prob, 32°F)

Growing season

223 days

frost-free window

Warmest month

August

avg high 76.7°F

Month-by-month typical weather in Sammamish

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Snoqualmie Falls, WA (9.9 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	46.4	35.8	41.1	8.6	1.5
February	49.6	35.3	42.4	5.8	0.2
March	53.7	37.2	45.4	6.7	0.3
April	58.9	40.1	49.5	5.3	0
May	64.1	46.1	55.1	4	0
June	69	50.6	59.8	3.2	0
July	75.8	54	64.9	1.2	0
August	76.7	53.7	65.2	1.2	0
September	70.4	49.1	59.7	3	0
October	59.5	43.5	51.5	6.2	0
November	51.1	38.3	44.7	9.5	0.1
December	45.8	35.7	40.7	8.4	1.5

What to plant when in Sammamish

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: February 16 · Transplant out: April 6
Peppers	warm	Start seeds indoors: February 2 · Transplant out: April 13
Cucumbers	warm	Direct sow: April 6
Zucchini / squash	warm	Direct sow: April 6
Bush beans	warm	Direct sow: April 6
Sweet corn	warm	Direct sow: April 6
Basil	warm	Transplant out: April 6
Peas	cool	Sow (spring): February 23 · Sow (fall): September 12
Spinach	cool	Sow (spring): February 16 · Sow (fall): September 12
Lettuce	cool	Sow (spring): March 2 · Sow (fall): September 12
Kale	cool	Transplant (spring): March 9 · Sow (fall): August 29
Broccoli	cool	Transplant (spring): March 16
Carrots	cool	Sow (spring): March 9 · Sow (fall): August 29
Onions	cool	Transplant (spring): March 2
Potatoes	cool	Plant seed potatoes: March 16
Radishes	cool	Sow (spring): March 2 · Sow (fall): September 26

Dates are computed from Sammamish's average frost dates using standard cool-/warm-season timing. They're a starting point — a cold spring, a warm microclimate, or a fast-maturing variety can shift them by a week or two.

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Gear that helps you plant on time

Some links below are Amazon affiliate links (tag theboringthin-20). If you buy through them we may earn a small commission at no extra cost to you — it keeps this almanac free. We only list generic, genuinely-useful categories.

Soil thermometer →Know when the ground is warm enough to sow — the honest signal, not the calendar.Seed-starting trays + dome →Start tomatoes & peppers indoors on the schedule below.Seedling heat mat →Warms the soil for faster, more even germination indoors.Floating row cover / frost cloth →Buys you 4–8°F to beat an early or late frost.Raised garden bed kit →Warms and drains faster in spring than in-ground soil.Garden gloves →Basic kit for transplant day.

Nearby cities in Washington

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Sources & method. Hardiness zone: 2023 USDA Plant Hardiness Zone Map (PRISM Climate Group, Oregon State University). Frost dates & growing season: NOAA/NCEI 1991–2020 U.S. Climate Normals, nearest station with published freeze normals — Snoqualmie Falls, WA, 9.9 mi (confidence: high). Monthly weather normals: Snoqualmie Falls, WA, 9.9 mi (confidence: high). ZIP centroid from U.S. Census 2023 ZCTA data. Frost dates are the 50%-probability date — half of years frost occurs outside the stated date. Nothing here is invented; where the nearest station is far, we say so. Last updated 2026-07-22.