Frost Dates for 97478 — Springfield, Oregon

Half of springs at Leaburg 1 SW, OR see their last 32°F night by April 3; only one in ten is past it by March 5, and one in ten still has one after May 2. Planting tender crops after April 16 leaves a 30% risk of a frost on them, after April 24 20%, and after May 2 10%. The 29 days between the even-odds date and the one-in-ten date is wider than at 82% 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 11 in half of years, as early as October 21 one year in ten, and holds off past December 5 one year in ten. A hard freeze of 28°F follows 23 days later, around December 4; in spring the one-in-ten date for 28°F is March 26, 37 days before the 32°F one. The freeze-free season lasts 220 days in a typical year, longer than at 63% of the 103 Oregon stations; it reaches 256 days one year in ten and falls short of 186 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 30 days longer, to about May 3, and return around October 23. Nights of 24°F, cold enough to damage hardier plants, come in 70% of winters and 16°F in 10%.

August is the warmest month at Leaburg 1 SW, OR, averaging 84°F by day and 51°F at night; December is the coldest at 47°F and 35°F. A freezing night is all but certain in every month from December to February (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, March still brings one in 85% of years and April still brings one in 49% of years and May still brings one in 13% of years.

Warmth for growing adds up to 2,343 growing degree days a year (base 50°F), more than at 61% of the 103 Oregon stations. 29% of them (675) have built up by the end of June, and August adds the most, 550. Precipitation totals 66.7 inches a year, most in December (10.7") and least in July (0.5"); May to September bring 15% of it.

The nearest other station, Lookout Pt Dam, OR, 13 miles southeast of Springfield, has a last frost 27 days earlier (March 7), a first frost 16 days later (November 27), a season 43 days longer.

Measurable snow is rare here: only 7 of 27 winters from 1991 to 2020 recorded 0.1 inch or more at Lookout Pt Dam, OR, 13.1 miles away, so there is no typical first-snow date to plan around.

ZIP 97478 is 11 miles from Leaburg 1 SW, OR, which stands at 675 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 97478 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.