Frost Dates for 83639 — Marsing, Idaho

Half of springs at Deer Flat Dam, ID see their last 32°F night by April 23; only one in ten is past it by April 5, and one in ten still has one after May 9. Planting tender crops after April 29 leaves a 30% risk of a frost on them, after May 3 20%, and after May 9 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 18 in half of years, as early as October 2 one year in ten, and holds off past November 1 one year in ten. A hard freeze of 28°F follows 12 days later, around October 30; in spring the one-in-ten date for 28°F is April 25, 14 days before the 32°F one. The freeze-free season lasts 178 days in a typical year, longer than at 90% of the 67 Idaho stations; it reaches 199 days one year in ten and falls short of 156 one year in ten. On average 106 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 14 days longer, to about May 7, and return around October 4. Severe cold of 16°F or below comes every winter, usually between December 4 and February 9.

July is the warmest month at Deer Flat Dam, ID, averaging 90°F by day and 59°F at night; December is the coldest at 40°F and 24°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 26% of years.

Warmth for growing adds up to 2,992 growing degree days a year (base 50°F), more than at 88% of the 67 Idaho stations. 31% of them (938) have built up by the end of June, and July adds the most, 761. Precipitation totals 10.2 inches a year, most in January (1.2") and least in August (0.2"); May to September bring 27% of it.

The nearest other station, Homedale 1 SE, ID, 6 miles northwest of Marsing and 280 feet lower, has a last frost 1 day later (April 24), a first frost 9 days earlier (October 9), a season 9 days shorter.

The first measurable snow (0.1 inch or more) in Marsing usually arrives around December 18, and the last of the season around January 28. Those are the middle dates across the winters of 1991–2020 at Homedale 1 SE, ID, 6.4 miles away: half of years saw snow earlier, half later. Snow fell in 81% of those winters. The last 32°F night of spring typically comes 85 days after the last snow.

ZIP 83639 is 6 miles from Deer Flat Dam, ID, which stands at 2,510 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 83607 (Caldwell). The 2023 USDA Plant Hardiness Zone Map lists ZIP 83639 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.