Frost Dates for 80435 — Dillon, Colorado

Half of springs at Cabin Creek, CO see their last 32°F night by June 6; only one in ten is past it by May 25, and one in ten still has one after June 21. Planting tender crops after June 13 leaves a 30% risk of a frost on them, after June 16 20%, and after June 21 10%. The 15 days between the even-odds date and the one-in-ten date is wider than at 56% of the 110 Colorado stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 19 in half of years, as early as September 5 one year in ten, and holds off past September 30 one year in ten. A hard freeze of 28°F follows 7 days later, around September 26; in spring the one-in-ten date for 28°F is June 9, 12 days before the 32°F one. The freeze-free season lasts 103 days in a typical year, shorter than at 83% of the 110 Colorado stations; it reaches 120 days one year in ten and falls short of 83 one year in ten. On average 234 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 13 days longer, to about June 19, and return around September 5. Severe cold of 16°F or below comes every winter, usually between October 22 and April 26.

July is the warmest month at Cabin Creek, CO, averaging 69°F by day and 46°F at night; February is the coldest at 32°F and 12°F. A freezing night is all but certain in every month from September 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 74% of years.

Warmth for growing adds up to 612 growing degree days a year (base 50°F), fewer than at 97% of the 110 Colorado stations. 21% of them (130) have built up by the end of June, and July adds the most, 234. Precipitation totals 21.7 inches a year, most in April (2.8") and least in January (1.0"); May to September bring 50% of it.

The nearest other station, Georgetown, CO, 16 miles northeast of Dillon and 1,500 feet lower, has a last frost 7 days earlier (May 30), the same first-frost date, a season 9 days longer.

The first measurable snow (0.1 inch or more) in Dillon usually arrives around October 7, and the last of the season around May 25. Those are the middle dates across the winters of 1991–2020 at Dillon 1 E, CO, 3.2 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 12 days after the last snow.

ZIP 80435 is 15 miles from Cabin Creek, CO, which stands at 10,020 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 80435 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.