Frost Dates for 97378 — Sheridan, Oregon

Half of springs at Dallas 2 NE, OR see their last 32°F night by April 16; only one in ten is past it by March 21, and one in ten still has one after May 5. Planting tender crops after April 25 leaves a 30% risk of a frost on them, after April 29 20%, and after May 5 10%. The 19 days between the even-odds date and the one-in-ten date is narrower than at 70% of the 103 Oregon stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 1 in half of years, as early as October 13 one year in ten, and holds off past November 22 one year in ten. A hard freeze of 28°F follows 19 days later, around November 20; in spring the one-in-ten date for 28°F is April 8, 27 days before the 32°F one. The freeze-free season lasts 199 days in a typical year, longer than at 50% of the 103 Oregon stations; it reaches 231 days one year in ten and falls short of 173 one year in ten. On average 49 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 20 days longer, to about May 6, and return around October 13. Nights of 24°F, cold enough to damage hardier plants, come in 93% of winters and 16°F in 18%.

August is the warmest month at Dallas 2 NE, OR, averaging 83°F by day and 52°F at night; December is the coldest at 46°F and 35°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 72% of years and May still brings one in 17% of years.

Warmth for growing adds up to 2,317 growing degree days a year (base 50°F), more than at 58% of the 103 Oregon stations. 28% of them (653) have built up by the end of June, and August adds the most, 546. Precipitation totals 47.9 inches a year, most in December (8.7") and least in July (0.3"); May to September bring 13% of it.

The nearest other station, Laurel Mountain, OR, 14 miles southwest of Sheridan and 3,299 feet higher, has a last frost 34 days later (May 20), a first frost 9 days earlier (October 23), a season 42 days shorter.

Measurable snow is rare here: only 9 of 27 winters from 1991 to 2020 recorded 0.1 inch or more at Willamina, OR, 3.7 miles away, so there is no typical first-snow date to plan around.

ZIP 97378 is 11 miles from Dallas 2 NE, OR, which stands at 290 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 97338 (Dallas). The 2023 USDA Plant Hardiness Zone Map lists ZIP 97378 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.