Frost Dates for 80466 — Nederland, Colorado

Half of springs at Boulder 14 W, CO see their last 32°F night by June 21; only one in ten is past it by June 7, and one in ten still has one after July 4. Planting tender crops after June 27 leaves a 30% risk of a frost on them, after June 30 20%, and after July 4 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 67% of the 110 Colorado stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 2 in half of years, as early as August 17 one year in ten, and holds off past September 15 one year in ten. A hard freeze of 28°F follows 12 days later, around September 14; in spring the one-in-ten date for 28°F is June 20, 14 days before the 32°F one. The freeze-free season lasts 71 days in a typical year, the shortest of the 110 Colorado stations; it reaches 90 days one year in ten and falls short of 51 one year in ten. On average 244 nights a year drop to 32°F or below. Severe cold of 16°F or below comes every winter, usually between October 17 and April 30.

July is the warmest month at Boulder 14 W, CO, averaging 68°F by day and 43°F at night; February is the coldest at 28°F and 12°F. A freezing night is all but certain in every month from September to June (a 90% chance or more). No month is safe from a 32°F night: even the warmest has at least a 10% chance. In spring, July still brings one in 19% of years.

Warmth for growing adds up to 385 growing degree days a year (base 50°F), the fewest of the 110 Colorado stations. 15% of them (59) have built up by the end of June, and July adds the most, 170. Precipitation totals 34.0 inches a year, most in April (4.8") and least in June (2.0"); May to September bring 39% of it.

The nearest other station, Coal Creek Canyon, CO, 8 miles southeast of Nederland and 878 feet lower, has a last frost 16 days earlier (June 5), a first frost 14 days later (September 16), a season 32 days longer.

The first measurable snow (0.1 inch or more) in Nederland usually arrives around October 9, and the last of the season around May 14. Those are the middle dates across the winters of 1991–2020 at Nederland 2.61 NNE, CO, 1.9 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 38 days after the last snow.

ZIP 80466 is 5 miles from Boulder 14 W, CO, which stands at 9,828 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 80466 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.