Frost Dates for 97470 — Roseburg, Oregon

Half of springs at Roseburg Regional Airport, OR see their last 32°F night by March 19; only one in ten is past it by February 18, and one in ten still has one after April 13. Planting tender crops after March 30 leaves a 30% risk of a frost on them, after April 3 20%, and after April 13 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 20 in half of years, as early as October 27 one year in ten, and holds off past December 17 one year in ten. A hard freeze of 28°F follows 21 days later, around December 11; in spring the one-in-ten date for 28°F is March 12, 32 days before the 32°F one. The freeze-free season lasts 245 days in a typical year, longer than at 82% of the 103 Oregon stations; it reaches 285 days one year in ten and falls short of 208 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 30 days longer, to about April 18, and return around October 29. Nights of 24°F, cold enough to damage hardier plants, come in 55% of winters and 16°F in 6%.

July is the warmest month at Roseburg Regional Airport, OR, averaging 86°F by day and 57°F at night; December is the coldest at 48°F and 37°F. A freezing night is all but certain in December (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 85% of years and March still brings one in 64% of years and April still brings one in 25% of years.

Warmth for growing adds up to 3,007 growing degree days a year (base 50°F), more than at 90% of the 103 Oregon stations. 31% of them (936) have built up by the end of June, and July adds the most, 669. Precipitation totals 32.1 inches a year, most in December (6.1") and least in August (0.2"); May to September bring 14% of it.

The nearest other station, Roseburg Kqen, OR, 1 mile southwest of Roseburg, has a last frost 4 days later (March 23), a first frost 2 days earlier (November 18), a season 8 days shorter.

Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Roseburg Kqen, OR, 1.2 miles away, so there is no typical first-snow date to plan around.

ZIP 97470 is under a mile from Roseburg Regional Airport, OR, which stands at 525 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 97470 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.