Frost Dates for 97361 — Monmouth, Oregon

Half of springs at Falls City 2 SSW, OR see their last 32°F night by April 18; only one in ten is past it by March 27, and one in ten still has one after May 6. Planting tender crops after April 27 leaves a 30% risk of a frost on them, after May 1 20%, and after May 6 10%. The 18 days between the even-odds date and the one-in-ten date is narrower than at 77% of the 103 Oregon stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 7 in half of years, as early as October 21 one year in ten, and holds off past November 24 one year in ten. A hard freeze of 28°F follows 16 days later, around November 23; in spring the one-in-ten date for 28°F is April 5, 31 days before the 32°F one. The freeze-free season lasts 202 days in a typical year, longer than at 53% of the 103 Oregon stations; it reaches 230 days one year in ten and falls short of 176 one year in ten. On average 70 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 21 days longer, to about May 9, and return around October 21. Nights of 24°F, cold enough to damage hardier plants, come in 94% of winters and 16°F in 25%.

August is the warmest month at Falls City 2 SSW, OR, averaging 81°F by day and 50°F at night; January is the coldest at 45°F and 33°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 79% of years and May still brings one in 22% of years.

Warmth for growing adds up to 1,872 growing degree days a year (base 50°F), fewer than at 66% of the 103 Oregon stations. 25% of them (459) have built up by the end of June, and August adds the most, 482. Precipitation totals 81.3 inches a year, most in December (16.4") and least in July (0.4"); May to September bring 9% of it.

The nearest other station, Dallas 2 NE, OR, 11 miles north of Monmouth and 400 feet lower, has a last frost 2 days earlier (April 16), a first frost 6 days earlier (November 1), a season 3 days shorter.

The first measurable snow (0.1 inch or more) in Monmouth usually arrives around December 19, and the last of the season around March 6. Those are the middle dates across the winters of 1991–2020 at Falls City 2 SSW, OR, 8 miles away: half of years saw snow earlier, half later. Snow fell in 87% of those winters. The last 32°F night of spring typically comes 43 days after the last snow.

ZIP 97361 is 8 miles from Falls City 2 SSW, OR, which stands at 690 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 97361 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.