Frost dates / Washington / Olympia

Frost dates in Olympia, WA

The station on this page is OLYMPIA AP, WA US (USW00024227), 4.7 miles from the city point. Population in the Census 2024 estimate is 56,271.

Zone 8bUSDA average annual extreme minimum 15°F to 20°F, from ZIP 98505 (4.3 miles from the city point used on this page).

Median last 32°F is April 29. Median first 32°F is October 14. The 50% growing-season length is 169 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%	April 11	Earlier date. A last 32°F on or after this day is common.
50%	April 29	Median.
10%	May 15	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%	September 28	Earlier date. A first 32°F on or before this day is uncommon.
50%	October 14	Median.
90%	November 1	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%	195
50%	169
90%	144

28°F threshold

	10%	50%	90%
Last, on or after	April 29	April 5	March 12
First, on or before	October 9	November 1	November 24
Season at least	239 days	210 days	181 days

36°F threshold

	10%	50%	90%
Last, on or after	May 31	May 15	April 30
First, on or before	September 12	September 28	October 14
Season at least	158 days	135 days	113 days

Station OLYMPIA AP, WA US (USW00024227). Completeness flag S, 30 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 57.3 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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Olympia, WA

Zone 8bAverage annual extreme minimum 15°F to 20°F

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

Washington. Nearest qualified station: OLYMPIA AP, WA US (USW00024227), 4.7 miles. Median last 32°F April 29. Median first 32°F October 14. The 50% growing-season length is 169 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	May 15	April 29	April 11
First 32°F on or before	September 28	October 14	November 1

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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