Frost dates / Washington / Kennewick

Frost dates in Kennewick, WA

The station on this page is KENNEWICK, WA US (USC00454154), 3.7 miles from the city point. Population in the Census 2024 estimate is 86,728.

Zone 7bUSDA average annual extreme minimum 5°F to 10°F, from ZIP 99336 (1.1 miles from the city point used on this page).

Median last 32°F is March 28. Median first 32°F is October 30. The 50% growing-season length is 216 days. The green band runs from the median last frost to the median first frost. Thin ticks mark the 10%, 50%, and 90% dates.

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Last 32°F in spring

NCEI’s probability is the chance the last spring minimum of 32°F or lower occurs on or after the date.

Probability	Date	How to read it
90%	March 9	Earlier date. A last 32°F on or after this day is common.
50%	March 28	Median.
10%	April 10	Later date. A last 32°F on or after this day is uncommon.

First 32°F in fall

NCEI’s probability is the chance the first autumn minimum of 32°F or lower occurs on or before the date.

Probability	Date	How to read it
10%	October 18	Earlier date. A first 32°F on or before this day is uncommon.
50%	October 30	Median.
90%	November 15	Later date. A first 32°F on or before this day is common.

32°F growing-season length

Days between the last spring 32°F and the first autumn 32°F. The figure is a length the season meets or exceeds at that probability, from NCEI, not a subtraction done on this site.

Probability the season is at least this long	Days
10%	239
50%	216
90%	196

28°F threshold

	10%	50%	90%
Last, on or after	March 29	March 8	February 20
First, on or before	October 27	November 11	December 1
Season at least	273 days	246 days	223 days

36°F threshold

	10%	50%	90%
Last, on or after	April 30	April 14	March 30
First, on or before	October 7	October 21	November 2
Season at least	208 days	189 days	168 days

Station KENNEWICK, WA US (USC00454154). Completeness flag S, 27 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 100%. Freeze dates are conditional on that threshold occurring. Elevation 118.9 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

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Kennewick, WA

Zone 7bAverage annual extreme minimum 5°F to 10°F

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Washington. Nearest qualified station: KENNEWICK, WA US (USC00454154), 3.7 miles. Median last 32°F March 28. Median first 32°F October 30. The 50% growing-season length is 216 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	April 10	March 28	March 9
First 32°F on or before	October 18	October 30	November 15

Column order matches the NCEI file: for the last freeze, 10% is the later date and 90% is the earlier date. How to read the probabilities.

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Planting calendar

Frost dates for Washington are above. Planting windows appear for states with a cited extension guide. The fall and seed tools use the numbers you enter and the station dates.

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