Frost Dates for 83849 — Osburn, Idaho

Half of springs at Wallace, ID see their last 32°F night by May 5; only one in ten is past it by April 22, and one in ten still has one after May 21. Planting tender crops after May 11 leaves a 30% risk of a frost on them, after May 15 20%, and after May 21 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 66% of the 67 Idaho stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 2 in half of years, as early as September 17 one year in ten, and holds off past October 19 one year in ten. A hard freeze of 28°F follows 16 days later, around October 18; in spring the one-in-ten date for 28°F is May 2, 19 days before the 32°F one. The freeze-free season lasts 149 days in a typical year, longer than at 51% of the 67 Idaho stations; it reaches 170 days one year in ten and falls short of 127 one year in ten. On average 155 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 22 days longer, to about May 27, and return around September 19. Severe cold of 16°F or below comes every winter, usually between November 29 and February 28.

July is the warmest month at Wallace, ID, averaging 81°F by day and 51°F at night; December is the coldest at 33°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 66% of years.

Warmth for growing adds up to 1,716 growing degree days a year (base 50°F), fewer than at 85% of the 67 Idaho stations. 26% of them (453) have built up by the end of June, and July adds the most, 499. Precipitation totals 37.2 inches a year, most in November (4.8") and least in July (0.9"); May to September bring 25% of it.

The nearest other station, Kellogg, ID, 5 miles west of Osburn and 333 feet lower, has a last frost 9 days later (May 14), a first frost 6 days earlier (September 26), a season 18 days shorter.

The first measurable snow (0.1 inch or more) in Osburn usually arrives around November 8, and the last of the season around April 2. Those are the middle dates across the winters of 1991–2020 at Wallace, ID, 4.9 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 33 days after the last snow.

ZIP 83849 is 5 miles from Wallace, ID, which stands at 2,710 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 83849 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.