Frost dates / Washington / Pasco

Frost dates in Pasco, WA

The station on this page is PASCO TRI CITIES AP, WA US (USW00024163), 0.2 miles from the city point. Population in the Census 2024 estimate is 81,724.

Zone 7bUSDA average annual extreme minimum 5°F to 10°F, from ZIP 99336 (4.4 miles from the city point used on this page).

Median last 32°F is April 27. Median first 32°F is October 11. The 50% growing-season length is 168 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 8	Earlier date. A last 32°F on or after this day is common.
50%	April 27	Median.
10%	May 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%	September 28	Earlier date. A first 32°F on or before this day is uncommon.
50%	October 11	Median.
90%	October 27	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%	189
50%	168
90%	148

28°F threshold

	10%	50%	90%
Last, on or after	April 28	April 7	March 20
First, on or before	October 6	October 23	November 8
Season at least	224 days	197 days	173 days

36°F threshold

	10%	50%	90%
Last, on or after	May 23	May 9	April 27
First, on or before	September 15	September 29	October 13
Season at least	161 days	143 days	124 days

Station PASCO TRI CITIES AP, WA US (USW00024163). Completeness flag R, 21 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 124.1 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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Pasco, 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: PASCO TRI CITIES AP, WA US (USW00024163), 0.2 miles. Median last 32°F April 27. Median first 32°F October 11. The 50% growing-season length is 168 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	May 10	April 27	April 8
First 32°F on or before	September 28	October 11	October 27

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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