Frost Dates for 97801 — Pendleton, Oregon

Half of springs at Pendleton Dwtn, OR see their last 32°F night by April 22; only one in ten is past it by April 3, and one in ten still has one after May 8. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 2 20%, and after May 8 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 91% of the 103 Oregon stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 9 in half of years, as early as September 27 one year in ten, and holds off past October 26 one year in ten. A hard freeze of 28°F follows 15 days later, around October 24; in spring the one-in-ten date for 28°F is April 21, 17 days before the 32°F one. The freeze-free season lasts 170 days in a typical year, shorter than at 70% of the 103 Oregon stations; it reaches 196 days one year in ten and falls short of 148 one year in ten. On average 109 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 15 days longer, to about May 7, and return around September 29. Severe cold of 16°F or below comes in 96% of winters, usually between December 5 and February 8.

July is the warmest month at Pendleton Dwtn, OR, averaging 90°F by day and 56°F at night; December is the coldest at 44°F and 28°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 27% of years.

Warmth for growing adds up to 2,825 growing degree days a year (base 50°F), more than at 84% of the 103 Oregon stations. 31% of them (880) have built up by the end of June, and July adds the most, 719.

The nearest other station, Hermiston Municipal Airport, OR, 25 miles northwest of Pendleton and 399 feet lower, has a last frost 4 days later (April 26), a first frost 1 day later (October 10), a season 3 days shorter.

The first measurable snow (0.1 inch or more) in Pendleton usually arrives around November 28, and the last of the season around March 2. Those are the middle dates across the winters of 1991–2020 at Pendleton WFO, OR, 3.5 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 51 days after the last snow.

ZIP 97801 is under a mile from Pendleton Dwtn, OR, which stands at 1,040 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 97801 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.