Frost Dates for 97761 — Warm Springs, Oregon

Half of springs at Pelton Dam, OR see their last 32°F night by May 5; only one in ten is past it by April 21, and one in ten still has one after May 29. Planting tender crops after May 13 leaves a 30% risk of a frost on them, after May 18 20%, and after May 29 10%. The 24 days between the even-odds date and the one-in-ten date is wider than at 60% 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 7 in half of years, as early as September 24 one year in ten, and holds off past October 22 one year in ten. A hard freeze of 28°F follows 13 days later, around October 20; in spring the one-in-ten date for 28°F is May 7, 22 days before the 32°F one. The freeze-free season lasts 154 days in a typical year, shorter than at 78% of the 103 Oregon stations; it reaches 175 days one year in ten and falls short of 128 one year in ten. On average 130 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 23 days longer, to about May 28, and return around September 26. Severe cold of 16°F or below comes in 97% of winters, usually between December 3 and February 11.

July is the warmest month at Pelton Dam, OR, averaging 92°F by day and 53°F at night; December is the coldest at 42°F and 27°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 65% of years.

Warmth for growing adds up to 2,721 growing degree days a year (base 50°F), more than at 79% of the 103 Oregon stations. 29% of them (790) have built up by the end of June, and July adds the most, 697. Precipitation totals 10.5 inches a year, most in December (1.6") and least in July (0.3"); May to September bring 27% of it.

The nearest other station, Madras 2 N, OR, 14 miles southeast of Warm Springs and 1,033 feet higher, has a last frost 14 days later (May 19), a first frost 3 days earlier (October 4), a season 18 days shorter.

The first measurable snow (0.1 inch or more) in Warm Springs usually arrives around December 4, and the last of the season around February 22. Those are the middle dates across the winters of 1991–2020 at Madras 2 N, OR, 13.6 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 72 days after the last snow.

ZIP 97761 is 7 miles from Pelton Dam, OR, which stands at 1,410 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 97761 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.