Frost dates for Greeley Unc, CO
At Greeley Unc, the median last spring frost (32°F) is May 2 and the median first fall frost is Oct 8, for a typical growing season of 159 days. For a 90% chance that the last frost has passed, wait until May 14. Nearby ZIP codes are in USDA hardiness zones 5a to 5b.
- May 2Last spring frost (median)50% chance of 32°F after this date
- May 14Safer planting date10% chance of 32°F after this date
- Oct 8First fall frost (median)50% chance of 32°F by this date
- 159 daysGrowing season (median)between 32°F freezes
USDA hardiness zone 5a (-20 to -15°F) · see all zone 5a frost dates
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 1 | May 12 | May 26 |
| 32°F | Apr 17 | May 2 | May 14 |
| 28°F | Apr 5 | Apr 20 | May 5 |
| 24°F | Mar 19 | Apr 6 | Apr 24 |
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 11 |
| 32°F | Sep 26 | Oct 8 | Oct 21 |
| 28°F | Oct 4 | Oct 18 | Nov 1 |
| 24°F | Oct 13 | Oct 28 | Nov 10 |
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 | 121 days | 139 days | 156 days |
| 32°F | 139 days | 159 days | 178 days |
| 28°F | 158 days | 179 days | 200 days |
| 24°F | 180 days | 202 days | 224 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 80620 | 5b | -15 to -10°F | 3 km |
| 80631 | 5a | -20 to -15°F | 5 km |
| 80634 | 5b | -15 to -10°F | 8 km |
| 80645 | 5a | -20 to -15°F | 14 km |
| 80543 | 5b | -15 to -10°F | 15 km |
| 80623 | 5a | -20 to -15°F | 15 km |
| 80615 | 5a | -20 to -15°F | 17 km |
| 80651 | 5b | -15 to -10°F | 21 km |
| 80644 | 5a | -20 to -15°F | 24 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 USC00053553, at 40.4022, -104.6992, elevation 1437 m (4,715 ft).
- Data quality: Standard (24+ years of data), 25 years of freeze data.
- Average days per year at or below 32°F: 153.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Loveland 2N (33 km)
- Fort Collins 4 E (34 km)
- Fort Collins (38 km)
- Briggsdale (41 km)
- Longmont 2 ESE (41 km)
- Waterdale (43 km)
- Nunn 7 NNE (45 km)
- Brighton 3 SE (52 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.