Frost Dates for 83301 — Twin Falls, Idaho

Half of springs at Twin Falls Sun Vly Regional Airport, ID see their last 32°F night by May 9; only one in ten is past it by April 25, and one in ten still has one after May 28. Planting tender crops after May 15 leaves a 30% risk of a frost on them, after May 21 20%, and after May 28 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 October 4 in half of years, as early as September 20 one year in ten, and holds off past October 20 one year in ten. A hard freeze of 28°F follows 11 days later, around October 15; in spring the one-in-ten date for 28°F is May 11, 17 days before the 32°F one. The freeze-free season lasts 147 days in a typical year, shorter than at 52% of the 67 Idaho stations; it reaches 170 days one year in ten and falls short of 122 one year in ten. On average 139 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 19 days longer, to about May 28, and return around September 23. Severe cold of 16°F or below comes every winter, usually between November 16 and February 23.

July is the warmest month at Twin Falls Sun Vly Regional Airport, ID, averaging 88°F by day and 58°F at night; December is the coldest at 37°F and 20°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 74% of years.

Warmth for growing adds up to 2,521 growing degree days a year (base 50°F), more than at 63% of the 67 Idaho stations. 27% of them (680) have built up by the end of June, and July adds the most, 714. Precipitation totals 10.3 inches a year, most in May (1.5") and least in July (0.3"); May to September bring 36% of it.

The nearest other station, Twin Falls 6 E, ID, 7 miles east of Twin Falls and 191 feet lower, has a last frost 3 days earlier (May 6), a first frost 1 day earlier (October 3), a season 3 days longer.

The first measurable snow (0.1 inch or more) in Twin Falls usually arrives around November 22, and the last of the season around March 28. Those are the middle dates across the winters of 1991–2020 at Twin Falls 6 E, ID, 6.7 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 42 days after the last snow.

ZIP 83301 is 3 miles from Twin Falls Sun Vly Regional Airport, ID, which stands at 4,151 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 83301 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.