Frost dates / Oregon / Gresham

Frost dates in Gresham, OR

The station on this page is PORTLAND TROUTDALE AP, OR US (USW00024242), 3.7 miles from the city point. Population in the Census 2024 estimate is 111,507.

Zone 9aUSDA average annual extreme minimum 20°F to 25°F, from ZIP 97030 (0.7 miles from the city point used on this page).

Median last 32°F is March 16. Median first 32°F is November 20. The 50% growing-season length is 250 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%	February 18	Earlier date. A last 32°F on or after this day is common.
50%	March 16	Median.
10%	April 12	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 30	Earlier date. A first 32°F on or before this day is uncommon.
50%	November 20	Median.
90%	December 17	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%	288
50%	250
90%	216

28°F threshold

	10%	50%	90%
Last, on or after	March 10	February 14	December 27
First, on or before	November 15	December 15	February 3
Season at least	358 days	311 days	268 days

36°F threshold

	10%	50%	90%
Last, on or after	May 4	April 19	March 27
First, on or before	October 11	October 30	November 22
Season at least	226 days	198 days	171 days

Station PORTLAND TROUTDALE AP, OR US (USW00024242). Completeness flag R, 20 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 8.8 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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Gresham, OR

Zone 9aAverage annual extreme minimum 20°F to 25°F

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

Oregon. Nearest qualified station: PORTLAND TROUTDALE AP, OR US (USW00024242), 3.7 miles. Median last 32°F March 16. Median first 32°F November 20. The 50% growing-season length is 250 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	April 12	March 16	February 18
First 32°F on or before	October 30	November 20	December 17

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 Oregon 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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