Frost dates for Alamosa San Luis Airport, CO
At Alamosa San Luis Airport, the median last spring frost (32°F) is Jun 7 and the median first fall frost is Sep 15, for a typical growing season of 98 days. For a 90% chance that the last frost has passed, wait until Jun 24. Nearby ZIP codes are in USDA hardiness zones 4b to 5b.
- Jun 7Last spring frost (median)50% chance of 32°F after this date
- Jun 24Safer planting date10% chance of 32°F after this date
- Sep 15First fall frost (median)50% chance of 32°F by this date
- 98 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 |
|---|---|---|---|
| 32°F | May 24 | Jun 7 | Jun 24 |
| 28°F | May 7 | May 23 | Jun 7 |
| 24°F | Apr 26 | May 8 | May 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 |
|---|---|---|---|
| 32°F | Sep 4 | Sep 15 | Sep 26 |
| 28°F | Sep 14 | Sep 25 | Oct 4 |
| 24°F | Sep 22 | Oct 2 | Oct 13 |
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 | 48 days | 72 days | 91 days |
| 32°F | 78 days | 98 days | 117 days |
| 28°F | 105 days | 124 days | 142 days |
| 24°F | 128 days | 146 days | 162 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 |
|---|---|---|---|
| 81101 | 4b | -25 to -20°F | 3 km |
| 81151 | 5a | -20 to -15°F | 26 km |
| 81123 | 5a | -20 to -15°F | 26 km |
| 81124 | 5a | -20 to -15°F | 28 km |
| 81144 | 5a | -20 to -15°F | 28 km |
| 81146 | 5a | -20 to -15°F | 29 km |
| 81140 | 5b | -15 to -10°F | 31 km |
| 81141 | 5a | -20 to -15°F | 31 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 USW00023061, at 37.4389, -105.8614, elevation 2296 m (7,533 ft).
- Data quality: Standard (24+ years of data), 29 years of freeze data.
- Average days per year at or below 32°F: 226.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Alamosa 1e (4 km)
- Waverly 1w (15 km)
- Blanca 4 NW (26 km)
- Manassa (31 km)
- Monte Vista 2w (33 km)
- Center 4 SSW (39 km)
- Great Sand Dunes National Park & Preserve (45 km)
- San Luis 1 S (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.