When is the last frost in Kennewick, WA?

The average last spring frost (50% probability of 32°F) in Kennewick is around March 28, based on NOAA/NCEI 1991–2020 normals at the Kennewick, WA station (3.6 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 Kennewick?

The average first fall frost in Kennewick, WA is around October 30, giving roughly a 216-day frost-free growing season.

What planting zone is Kennewick, WA?

Kennewick is in USDA plant hardiness zone 7b (average annual extreme minimum temperature 5 to 10°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Kennewick?

In Kennewick, WA the warmest month is July (avg high 91.3°F) and the coldest is January (avg low 29.2°F). It averages about 7.9″ of precipitation a year.

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Kennewick, WA Planting Calendar & Frost Dates

USDA hardiness zone 7b · ZIP 99336 · elevation 119′ · NOAA & USDA data

Kennewick is in USDA hardiness zone 7b (winters can dip to 5 to 10°F), with a growing season of about 216 days between the average last spring frost (March 28) and first fall frost (October 30). The warmest month is July (avg high 91.3°F); the coldest is January (avg low 29.2°F). It averages 7.9″ of precipitation a year. 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 5 to 10°F

Last spring frost

March 28

avg (50% prob, 32°F)

First fall frost

October 30

avg (50% prob, 32°F)

Growing season

216 days

frost-free window

Warmest month

July

avg high 91.3°F

Month-by-month typical weather in Kennewick

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Kennewick, WA (3.6 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	41.7	29.2	35.5	1.1	–
February	48.1	30.9	39.5	0.8	–
March	58.1	35.9	47	0.7	–
April	66.3	42.4	54.3	0.6	–
May	75.3	50.1	62.7	0.8	–
June	82	56.4	69.2	0.6	–
July	91.3	62.3	76.8	0.2	–
August	90.3	61.3	75.8	0.2	–
September	80.5	53.2	66.8	0.3	–
October	65.9	43.1	54.5	0.7	–
November	50.9	34.9	42.9	0.9	–
December	41.5	29.6	35.6	1.1	–

What to plant when in Kennewick

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: February 14 · Transplant out: April 4
Peppers	warm	Start seeds indoors: January 31 · Transplant out: April 11
Cucumbers	warm	Direct sow: April 4
Zucchini / squash	warm	Direct sow: April 4
Bush beans	warm	Direct sow: April 4
Sweet corn	warm	Direct sow: April 4
Basil	warm	Transplant out: April 4
Peas	cool	Sow (spring): February 21 · Sow (fall): September 4
Spinach	cool	Sow (spring): February 14 · Sow (fall): September 4
Lettuce	cool	Sow (spring): February 28 · Sow (fall): September 4
Kale	cool	Transplant (spring): March 7 · Sow (fall): August 21
Broccoli	cool	Transplant (spring): March 14
Carrots	cool	Sow (spring): March 7 · Sow (fall): August 21
Onions	cool	Transplant (spring): February 28
Potatoes	cool	Plant seed potatoes: March 14
Radishes	cool	Sow (spring): February 28 · Sow (fall): September 18

Dates are computed from Kennewick'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

Richland, WA Pasco, WA Yakima, WA Spokane, WA Auburn, WA Puyallup, WA Kent, WA Sammamish, WA

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 — Kennewick, WA, 3.6 mi (confidence: high). Monthly weather normals: Kennewick, WA, 3.6 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.