Frost Dates for 83263 — Preston, Idaho

Half of springs at Preston, ID see their last 32°F night by May 16; only one in ten is past it by May 2, and one in ten still has one after June 4. Planting tender crops after May 24 leaves a 30% risk of a frost on them, after May 28 20%, and after June 4 10%. The 19 days between the even-odds date and the one-in-ten date is wider than at 60% of the 67 Idaho stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 28 in half of years, as early as September 14 one year in ten, and holds off past October 14 one year in ten. A hard freeze of 28°F follows 12 days later, around October 10; in spring the one-in-ten date for 28°F is May 13, 22 days before the 32°F one. The freeze-free season lasts 133 days in a typical year, shorter than at 64% of the 67 Idaho stations; it reaches 156 days one year in ten and falls short of 110 one year in ten. On average 175 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 18 days longer, to about June 3, and return around September 17. Severe cold of 16°F or below comes every winter, usually between November 14 and March 8.

July is the warmest month at Preston, ID, averaging 89°F by day and 54°F at night; January is the coldest at 32°F and 15°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 15% of years.

Warmth for growing adds up to 2,280 growing degree days a year (base 50°F), more than at 54% of the 67 Idaho stations. 27% of them (625) have built up by the end of June, and July adds the most, 662. Precipitation totals 17.3 inches a year, most in May (2.2") and least in July (0.7"); May to September bring 37% of it.

The nearest other station, Trenton, UT, 18 miles south of Preston and 264 feet lower, has a last frost 1 day later (May 17), a first frost 10 days earlier (September 18), a season 12 days shorter.

The first measurable snow (0.1 inch or more) in Preston usually arrives around November 5, and the last of the season around April 13. Those are the middle dates across the winters of 1991–2020 at Preston, ID, 5.8 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 83263 is 6 miles from Preston, ID, which stands at 4,719 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 83263 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.