Frost Dates for 97738 — Hines, Oregon

Half of springs at O O Rch, OR see their last 32°F night by June 11; only one in ten is past it by May 18, and one in ten still has one after July 1. Planting tender crops after June 21 leaves a 30% risk of a frost on them, after June 26 20%, and after July 1 10%. The 20 days between the even-odds date and the one-in-ten date is narrower than at 64% of the 103 Oregon stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 6 in half of years, as early as August 19 one year in ten, and holds off past September 22 one year in ten. A hard freeze of 28°F follows 13 days later, around September 19; in spring the one-in-ten date for 28°F is June 20, 11 days before the 32°F one. The freeze-free season lasts 88 days in a typical year, shorter than at 98% of the 103 Oregon stations; it reaches 116 days one year in ten and falls short of 61 one year in ten. On average 197 nights a year drop to 32°F or below. Severe cold of 16°F or below comes every winter, usually between November 6 and February 28.

July is the warmest month at O O Rch, OR, averaging 85°F by day and 46°F at night; January is the coldest at 38°F and 20°F. A freezing night is all but certain in every month from September to May (a 90% chance or more). No month is safe from a 32°F night: even the warmest has at least a 10% chance. In spring, June still brings one in 65% of years and July still brings one in 11% of years.

Warmth for growing adds up to 1,464 growing degree days a year (base 50°F), fewer than at 91% of the 103 Oregon stations. 22% of them (323) have built up by the end of June, and July adds the most, 485.

The nearest other station, Burns Municipal Airport, OR, 15 miles northeast of Hines, has the same 50% last-frost date, the same first-frost date, a season 3 days shorter.

The first measurable snow (0.1 inch or more) in Hines usually arrives around November 17, and the last of the season around March 12. Those are the middle dates across the winters of 1991–2020 at Squaw Butte-Northern Great Bas, OR, 25.6 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 91 days after the last snow.

ZIP 97738 is 14 miles from O O Rch, OR, which stands at 4,136 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 97738 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.