Frost Dates for 80422 — Black Hawk, Colorado

Half of springs at Coal Creek Canyon, CO see their last 32°F night by June 5; only one in ten is past it by May 23, and one in ten still has one after June 19. Planting tender crops after June 11 leaves a 30% risk of a frost on them, after June 14 20%, and after June 19 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 45% of the 110 Colorado stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 16 in half of years, as early as September 2 one year in ten, and holds off past September 28 one year in ten. A hard freeze of 28°F follows 10 days later, around September 26; in spring the one-in-ten date for 28°F is June 5, 14 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 122 days one year in ten and falls short of 83 one year in ten. On average 211 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 June 19, and return around September 4. Severe cold of 16°F or below comes every winter, usually between October 23 and April 23.

July is the warmest month at Coal Creek Canyon, CO, averaging 73°F by day and 48°F at night; December is the coldest at 33°F and 15°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 68% of years.

Warmth for growing adds up to 917 growing degree days a year (base 50°F), fewer than at 92% of the 110 Colorado stations. 20% of them (186) have built up by the end of June, and July adds the most, 320. Precipitation totals 25.8 inches a year, most in April (3.8") and least in January (1.0"); May to September bring 50% of it.

The nearest other station, Georgetown, CO, 13 miles southwest of Black Hawk and 430 feet lower, has a last frost 6 days earlier (May 30), a first frost 3 days later (September 19), a season 9 days longer.

The first measurable snow (0.1 inch or more) in Black Hawk usually arrives around September 27, and the last of the season around May 30. Those are the middle dates across the winters of 1991–2020 at Coal Creek Canyon, CO, 8.7 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 6 days after the last snow.

ZIP 80422 is 9 miles from Coal Creek Canyon, CO, which stands at 8,950 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 80422 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.