Frost Dates for 83522 — Cottonwood, Idaho

Half of springs at Cottonwood 2 WSW, ID see their last 32°F night by May 6; only one in ten is past it by April 22, and one in ten still has one after May 26. Planting tender crops after May 15 leaves a 30% risk of a frost on them, after May 19 20%, and after May 26 10%. The 20 days between the even-odds date and the one-in-ten date is wider than at 69% of the 67 Idaho stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 13 in half of years, as early as September 28 one year in ten, and holds off past October 27 one year in ten. A hard freeze of 28°F follows 11 days later, around October 24; in spring the one-in-ten date for 28°F is May 10, 16 days before the 32°F one. The freeze-free season lasts 156 days in a typical year, longer than at 66% of the 67 Idaho stations; it reaches 181 days one year in ten and falls short of 132 one year in ten. On average 134 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 25 days longer, to about May 31, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 26 and February 21.

August is the warmest month at Cottonwood 2 WSW, ID, averaging 81°F by day and 56°F at night; December is the coldest at 36°F and 24°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 67% of years.

Warmth for growing adds up to 2,010 growing degree days a year (base 50°F), fewer than at 60% of the 67 Idaho stations. 22% of them (452) have built up by the end of June, and August adds the most, 578. Precipitation totals 22.6 inches a year, most in May (2.8") and least in August (0.8"); May to September bring 38% of it.

The nearest other station, Grangeville, ID, 15 miles southeast of Cottonwood and 645 feet lower, has a last frost 3 days later (May 9), a first frost 10 days earlier (October 3), a season 10 days shorter.

The first measurable snow (0.1 inch or more) in Cottonwood usually arrives around November 7, and the last of the season around April 13. Those are the middle dates across the winters of 1991–2020 at Cottonwood 2 WSW, ID, 0.6 miles away: half of years saw snow earlier, half later. Snow fell in 95% of those winters. The last 32°F night of spring typically comes 23 days after the last snow.

ZIP 83522 is under a mile from Cottonwood 2 WSW, ID, which stands at 3,945 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 83522 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.