Frost dates for Alamosa 1e, CO
At Alamosa 1e, the median last spring frost (32°F) is May 30 and the median first fall frost is Sep 17, for a typical growing season of 108 days. For a 90% chance that the last frost has passed, wait until Jun 13. Nearby ZIP codes are in USDA hardiness zone 4b.
- May 30Last spring frost (median)50% chance of 32°F after this date
- Jun 13Safer planting date10% chance of 32°F after this date
- Sep 17First fall frost (median)50% chance of 32°F by this date
- 108 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 | Jun 4 | Jun 14 | Jun 30 |
| 32°F | May 17 | May 30 | Jun 13 |
| 28°F | May 2 | May 16 | Jun 1 |
| 24°F | Apr 22 | May 4 | May 18 |
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 | Aug 19 | Sep 5 | Sep 16 |
| 32°F | Sep 4 | Sep 17 | Sep 27 |
| 28°F | Sep 16 | Sep 27 | Oct 5 |
| 24°F | Sep 25 | Oct 4 | Oct 16 |
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 | 60 days | 81 days | 98 days |
| 32°F | 91 days | 108 days | 126 days |
| 28°F | 114 days | 132 days | 149 days |
| 24°F | 135 days | 151 days | 167 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 |
|---|---|---|---|
| 81101 | 4b | -25 to -20°F | 0 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 USC00050128, at 37.4703, -105.8569, elevation 2298 m (7,540 ft).
- Data quality: Representative (10+ years), 12 years of freeze data.
- Average days per year at or below 32°F: 221.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Alamosa San Luis Airport (4 km)
- Waverly 1w (16 km)
- Blanca 4 NW (25 km)
- Monte Vista 2w (32 km)
- Manassa (34 km)
- Center 4 SSW (37 km)
- Great Sand Dunes National Park & Preserve (42 km)
- Del Norte 3ene (47 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.