Frost Dates for 97224 — Tigard, Oregon

Half of springs at Beaverton 2 SSW, OR see their last 32°F night by April 1; only one in ten is past it by March 5, and one in ten still has one after April 26. Planting tender crops after April 11 leaves a 30% risk of a frost on them, after April 18 20%, and after April 26 10%. The 25 days between the even-odds date and the one-in-ten date is wider than at 68% 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 6 in half of years, as early as October 19 one year in ten, and holds off past December 1 one year in ten. A hard freeze of 28°F follows 24 days later, around November 30; in spring the one-in-ten date for 28°F is March 26, 31 days before the 32°F one. The freeze-free season lasts 222 days in a typical year, longer than at 66% of the 103 Oregon stations; it reaches 254 days one year in ten and falls short of 186 one year in ten. On average 42 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 27 days longer, to about April 28, and return around October 21. Nights of 24°F, cold enough to damage hardier plants, come in 84% of winters and 16°F in 17%.

July is the warmest month at Beaverton 2 SSW, OR, averaging 82°F by day and 54°F at night; December is the coldest at 48°F and 34°F. A freezing night is all but certain in every month from December to February (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, March still brings one in 86% of years and April still brings one in 47% of years.

Warmth for growing adds up to 2,459 growing degree days a year (base 50°F), more than at 65% of the 103 Oregon stations. 31% of them (762) have built up by the end of June, and July adds the most, 566.

The nearest other station, Nature Park-Beaverton, OR, 7 miles northwest of Tigard, has a last frost 49 days earlier (February 11), a first frost 29 days later (December 5), a season 81 days longer.

Measurable snow is rare here: only 4 of 16 winters from 1991 to 2020 recorded 0.1 inch or more at Beaverton 2 SSW, OR, 3.8 miles away, so there is no typical first-snow date to plan around.

ZIP 97224 is 4 miles from Beaverton 2 SSW, OR, which stands at 270 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 97223 (Tigard). The 2023 USDA Plant Hardiness Zone Map lists ZIP 97224 in zone 9a, the band where the coldest night of the year averaged 20 to 25°F (-6.7 to -3.9°C) over 1991–2020; a zone describes winter lows, not frost dates.