Frost Dates for 83440 — Rexburg, Idaho

Half of springs at Rexburg Byu Idaho, ID see their last 32°F night by May 12; only one in ten is past it by April 29, and one in ten still has one after June 2. Planting tender crops after May 20 leaves a 30% risk of a frost on them, after May 27 20%, and after June 2 10%. The 21 days between the even-odds date and the one-in-ten date is wider than at 78% of the 67 Idaho stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.

In fall the first 32°F night comes by September 24 in half of years, as early as September 6 one year in ten, and holds off past October 8 one year in ten. A hard freeze of 28°F follows 13 days later, around October 7; in spring the one-in-ten date for 28°F is May 14, 19 days before the 32°F one. The freeze-free season lasts 132 days in a typical year, shorter than at 66% of the 67 Idaho stations; it reaches 154 days one year in ten and falls short of 107 one year in ten. On average 184 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 23 days longer, to about June 4, and return around September 11. Severe cold of 16°F or below comes every winter, usually between November 11 and March 16.

July is the warmest month at Rexburg Byu Idaho, ID, averaging 85°F by day and 52°F at night; January is the coldest at 30°F and 14°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 85% of years and June still brings one in 12% of years.

Warmth for growing adds up to 1,948 growing degree days a year (base 50°F), fewer than at 69% of the 67 Idaho stations. 27% of them (526) have built up by the end of June, and July adds the most, 573. Precipitation totals 12.6 inches a year, most in May (1.8") and least in July (0.6"); May to September bring 44% of it.

The nearest other station, Sugar City, ID, 6 miles northeast of Rexburg, has a last frost 17 days later (May 29), a first frost 11 days earlier (September 13), a season 26 days shorter.

The first measurable snow (0.1 inch or more) in Rexburg usually arrives around November 9, and the last of the season around April 3. Those are the middle dates across the winters of 1991–2020 at Rexburg Byu Idaho, ID, 1 miles away: half of years saw snow earlier, half later. Snow fell in 93% of those winters. The last 32°F night of spring typically comes 39 days after the last snow.

ZIP 83440 is 1 mile from Rexburg Byu Idaho, ID, which stands at 5,005 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 83440 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°C) over 1991–2020; a zone describes winter lows, not frost dates.