Frost dates for Blanca 4 NW, CO
At Blanca 4 NW, the median last spring frost (32°F) is May 25 and the median first fall frost is Sep 22, for a typical growing season of 117 days. For a 90% chance that the last frost has passed, wait until Jun 12. Nearby ZIP codes are in USDA hardiness zones 5a to 5b.
- May 25Last spring frost (median)50% chance of 32°F after this date
- Jun 12Safer planting date10% chance of 32°F after this date
- Sep 22First fall frost (median)50% chance of 32°F by this date
- 117 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 22 | Jun 5 | Jun 30 |
| 32°F | May 11 | May 25 | Jun 12 |
| 28°F | Apr 29 | May 13 | May 31 |
| 24°F | Apr 18 | May 1 | May 17 |
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 1 | Sep 13 | Sep 23 |
| 32°F | Sep 10 | Sep 22 | Oct 3 |
| 28°F | Sep 16 | Oct 1 | Oct 15 |
| 24°F | Sep 26 | Oct 10 | Oct 25 |
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 | 72 days | 96 days | 114 days |
| 32°F | 95 days | 117 days | 136 days |
| 28°F | 116 days | 139 days | 158 days |
| 24°F | 139 days | 160 days | 180 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 |
|---|---|---|---|
| 81123 | 5a | -20 to -15°F | 8 km |
| 81133 | 5b | -15 to -10°F | 22 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 USC00050776, at 37.4786, -105.5717, elevation 2350 m (7,709 ft).
- Data quality: Representative (10+ years), 18 years of freeze data.
- Average days per year at or below 32°F: 215.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Alamosa 1e (25 km)
- Alamosa San Luis Airport (26 km)
- Great Sand Dunes National Park & Preserve (29 km)
- San Luis 1 S (34 km)
- Sheep Mountain (40 km)
- Waverly 1w (41 km)
- Manassa (47 km)
- Monte Vista 2w (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.