Frost Dates for 81403 — Montrose, Colorado

Half of springs at Montrose #2, CO see their last 32°F night by April 28; only one in ten is past it by April 13, and one in ten still has one after May 12. Planting tender crops after May 3 leaves a 30% risk of a frost on them, after May 7 20%, and after May 12 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 October 14 in half of years, as early as October 1 one year in ten, and holds off past October 27 one year in ten. A hard freeze of 28°F follows 10 days later, around October 24; in spring the one-in-ten date for 28°F is April 30, 12 days before the 32°F one. The freeze-free season lasts 167 days in a typical year, longer than at 94% of the 110 Colorado stations; it reaches 186 days one year in ten and falls short of 148 one year in ten. On average 155 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 May 11, and return around October 3. Severe cold of 16°F or below comes every winter, usually between November 23 and February 26.

July is the warmest month at Montrose #2, CO, averaging 90°F by day and 59°F at night; January is the coldest at 40°F and 18°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 39% of years.

Warmth for growing adds up to 3,044 growing degree days a year (base 50°F), more than at 80% of the 110 Colorado stations. 33% of them (1,017) have built up by the end of June, and July adds the most, 766. Precipitation totals 9.3 inches a year, most in September (1.2") and least in January (0.5"); May to September bring 48% of it.

The nearest other station, Ridgway, CO, 13 miles southeast of Montrose and 1,260 feet higher, has a last frost 44 days later (June 11), a first frost 31 days earlier (September 13), a season 75 days shorter.

The first measurable snow (0.1 inch or more) in Montrose usually arrives around November 11, and the last of the season around April 3. Those are the middle dates across the winters of 1991–2020 at Montrose 1.2 WSW, CO, 11.8 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 25 days after the last snow.

ZIP 81403 is 13 miles from Montrose #2, CO, which stands at 5,789 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 81401 (Montrose). The 2023 USDA Plant Hardiness Zone Map lists ZIP 81403 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.