Frost Dates for 97080 — Gresham, Oregon

Half of springs at Portland Troutdale Airport, OR see their last 32°F night by March 16; only one in ten is past it by February 18, and one in ten still has one after April 12. Planting tender crops after March 27 leaves a 30% risk of a frost on them, after April 2 20%, and after April 12 10%. The 27 days between the even-odds date and the one-in-ten date is wider than at 75% of the 103 Oregon stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.

In fall the first 32°F night comes by November 20 in half of years, as early as October 30 one year in ten, and holds off past December 17 one year in ten. A hard freeze of 28°F follows 25 days later, around December 15; in spring the one-in-ten date for 28°F is March 10, 33 days before the 32°F one. The freeze-free season lasts 250 days in a typical year, longer than at 86% of the 103 Oregon stations; it reaches 288 days one year in ten and falls short of 216 one year in ten. On average 28 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 34 days longer, to about April 19, and return around October 30. Nights of 24°F, cold enough to damage hardier plants, come in 51% of winters and 16°F in 3%.

August is the warmest month at Portland Troutdale Airport, OR, averaging 82°F by day and 57°F at night; December is the coldest at 46°F and 37°F. A freezing night is all but certain in January (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 89% of years and March still brings one in 66% of years and April still brings one in 23% of years.

Warmth for growing adds up to 2,697 growing degree days a year (base 50°F), more than at 77% of the 103 Oregon stations. 31% of them (844) have built up by the end of June, and August adds the most, 608. Precipitation totals 40.7 inches a year, most in December (6.2") and least in July (0.6"); May to September bring 20% of it.

The nearest other station, Troutdale, OR, 5 miles north of Gresham, has a last frost 10 days later (March 26), a first frost 3 days earlier (November 17), a season 13 days shorter.

Measurable snow is rare here: only 5 of 27 winters from 1991 to 2020 recorded 0.1 inch or more at Troutdale, OR, 5.1 miles away, so there is no typical first-snow date to plan around.

ZIP 97080 is 5 miles from Portland Troutdale Airport, OR, which stands at 29 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 97080 in zone 8b, the band where the coldest night of the year averaged 15 to 20°F (-9.4 to -6.7°C) over 1991–2020; a zone describes winter lows, not frost dates.