Frost dates for Cortez, CO
At Cortez, the median last spring frost (32°F) is May 12 and the median first fall frost is Oct 7, for a typical growing season of 147 days. For a 90% chance that the last frost has passed, wait until May 31. Nearby ZIP codes are in USDA hardiness zones 6a to 7a.
- May 12Last spring frost (median)50% chance of 32°F after this date
- May 31Safer planting date10% chance of 32°F after this date
- Oct 7First fall frost (median)50% chance of 32°F by this date
- 147 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | May 13 | May 26 | Jun 12 |
| 32°F | Apr 30 | May 12 | May 31 |
| 28°F | Apr 14 | Apr 30 | May 14 |
| 24°F | Mar 30 | Apr 14 | May 1 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Sep 18 | Sep 30 | Oct 12 |
| 32°F | Sep 26 | Oct 7 | Oct 21 |
| 28°F | Oct 4 | Oct 17 | Nov 1 |
| 24°F | Oct 12 | Oct 29 | Nov 12 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 105 days | 125 days | 143 days |
| 32°F | 127 days | 147 days | 165 days |
| 28°F | 152 days | 171 days | 191 days |
| 24°F | 175 days | 196 days | 220 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
Closest ZIP codes (each is closer to another station)
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 81321 | 7a | 0 to 5°F | 13 km |
| 81330 | 7a | 0 to 5°F | 16 km |
| 81327 | 6b | -5 to 0°F | 20 km |
| 81334 | 7a | 0 to 5°F | 22 km |
| 81335 | 6b | -5 to 0°F | 25 km |
| 81328 | 6a | -10 to -5°F | 25 km |
| 81331 | 6b | -5 to 0°F | 30 km |
| 81320 | 6b | -5 to 0°F | 44 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USC00051886, at 37.3444, -108.5950, elevation 1880 m (6,167 ft).
- Data quality: Standard (24+ years of data), 28 years of freeze data.
- Average days per year at or below 32°F: 168.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Cortez Montezuma Co Airport (5 km)
- Cortez 8 SE (13 km)
- Mesa Verde National Park (19 km)
- Yellow Jacket 2w (24 km)
- Yellow Jacket 4ne (25 km)
- Mancos 1sw (25 km)
- Fort Lewis (50 km)
- Dove Creek (55 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.