Frost Dates for 97448 — Junction City, Oregon

Half of springs at Eugene Mahlon Sweet Airport, OR see their last 32°F night by April 11; only one in ten is past it by March 15, and one in ten still has one after May 9. Planting tender crops after April 25 leaves a 30% risk of a frost on them, after April 30 20%, and after May 9 10%. The 28 days between the even-odds date and the one-in-ten date is wider than at 80% 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 October 23 in half of years, as early as October 6 one year in ten, and holds off past November 13 one year in ten. A hard freeze of 28°F follows 19 days later, around November 11; in spring the one-in-ten date for 28°F is March 30, 40 days before the 32°F one. The freeze-free season lasts 196 days in a typical year, shorter than at 51% of the 103 Oregon stations; it reaches 227 days one year in ten and falls short of 162 one year in ten. On average 52 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 May 15, and return around October 7. Nights of 24°F, cold enough to damage hardier plants, come in 94% of winters and 16°F in 27%.

August is the warmest month at Eugene Mahlon Sweet Airport, OR, averaging 84°F by day and 52°F at night; December is the coldest at 47°F and 34°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 57% of years and May still brings one in 19% of years.

Warmth for growing adds up to 2,299 growing degree days a year (base 50°F), more than at 55% of the 103 Oregon stations. 28% of them (635) have built up by the end of June, and August adds the most, 555. Precipitation totals 40.9 inches a year, most in December (7.2") and least in July (0.3"); May to September bring 14% of it.

The nearest other station, Fern Ridge-Veneta, OR, 13 miles southwest of Junction City, has a last frost 7 days later (April 18), a first frost 2 days later (October 25), a season 7 days shorter.

Measurable snow is rare here: only 4 of 26 winters from 1991 to 2020 recorded 0.1 inch or more at Fern Ridge-Veneta, OR, 12.8 miles away, so there is no typical first-snow date to plan around.

ZIP 97448 is 5 miles from Eugene Mahlon Sweet Airport, OR, which stands at 353 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 8 other ZIP codes share the station; its figures are presented in full for 97402 (Eugene). The 2023 USDA Plant Hardiness Zone Map lists ZIP 97448 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.