Frost dates for 81123Blanca, CO
The average last spring frost in Blanca is May 25 and the average first fall frost is September 22, giving a typical growing season of about 117 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 25
- Average first fall frost
- Sep 22
- Growing season
- 117 days
Safer after Jun 12 (1-in-10 risk)
Possible by Sep 10 (1-in-10 risk)
Last frost typically in 210 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | May 22 · Jun 5 · Jun 30 | Sep 1 · Sep 13 · Sep 23 | 96 days | 100% |
| Frost / freeze (32°F) | May 11 · May 25 · Jun 12 | Sep 10 · Sep 22 · Oct 3 | 117 days | 100% |
| Hard freeze (28°F) | Apr 29 · May 13 · May 31 | Sep 16 · Oct 1 · Oct 15 | 139 days | 100% |
Planting calendar for Blanca
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Apr 24 – Jun 30 |
| Tomatoes | Transplant outdoors | Jun 10 – Jun 2 |
| Peppers | Start seeds indoors | Apr 24 – May 25 |
| Peppers | Transplant outdoors | Jun 24 – Jul 25 |
| Eggplant | Start seeds indoors | May 11 – Jun 9 |
| Eggplant | Transplant outdoors | Jun 24 – Jul 25 |
| Cucumbers | Sow outdoors | Jun 24 – Jun 12 |
| Summer squash | Sow outdoors | Jun 10 – Jul 25 |
| Winter squash & pumpkins | Sow outdoors | Jun 24 – Jul 25 |
| Snap beans | Sow outdoors | Jun 10 – Jul 5 |
| Sweet corn | Sow outdoors | Jun 10 – Jun 2 |
| Watermelon & cantaloupe | Sow outdoors | Jun 24 – Jul 25 |
| Okra | Sow outdoors | Jun 17 – Jul 10 |
| Peas | Sow outdoors (spring) | Apr 24 – Jun 9 |
| Potatoes | Plant outdoors (spring) | Apr 24 – Jun 24 |
| Onions | Start seeds indoors (spring) | Mar 13 – Apr 9 |
| Onions | Transplant outdoors (spring) | May 11 – Jun 9 |
| Broccoli | Start seeds indoors (spring) | Apr 6 – May 10 |
| Broccoli | Transplant outdoors (spring) | May 11 – Jun 9 |
| Broccoli | Start seeds indoors (fall) | May 23 – Jun 2 |
| Broccoli | Transplant outdoors (fall) | Jun 22 – Jul 3 |
| Cabbage | Start seeds indoors (spring) | Mar 27 – Apr 24 |
| Cabbage | Transplant outdoors (spring) | Apr 24 – May 25 |
| Cabbage | Start seeds indoors (fall) | May 13 – Jun 12 |
| Cabbage | Transplant outdoors (fall) | Jun 12 – Jul 13 |
| Leaf lettuce | Sow outdoors (spring) | Apr 24 – Jul 10 |
| Leaf lettuce | Sow outdoors (fall) | Jun 12 – Jul 29 |
| Spinach | Sow outdoors (spring) | Apr 17 – May 31 |
| Spinach | Sow outdoors (fall) | Jun 29 – Aug 3 |
| Radishes | Sow outdoors (spring) | Apr 24 – Jun 14 |
| Radishes | Sow outdoors (fall) | Jun 12 – Aug 13 |
| Kale | Sow outdoors (spring) | May 11 – May 31 |
| Kale | Sow outdoors (fall) | Jun 5 – Jul 13 |
| Carrots | Sow outdoors (spring) | May 25 – Jul 10 |
| Carrots | Sow outdoors (fall) | May 13 – Jun 28 |
| Garlic | Plant outdoors (fall) | Sep 12 – Oct 13 |
Where these dates come from
ZIP code 81123 is matched to the NOAA station Blanca 4 Nw, CO, 7.1 km away, at 7,709 ft elevation (34 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Blanca 4 Nw, CO (used) | 7,709 ft | May 25 | Sep 22 |
| San Luis 1 S, CO | 7,943 ft | May 31 | Sep 23 |
| Alamosa 1E, CO | 7,540 ft | May 30 | Sep 17 |
| Alamosa San Luis Ap, CO | 7,534 ft | Jun 7 | Sep 15 |
Frost dates near Blanca
- Fort Garland, CO 81133 · last May 25, first Sep 22
- Alamosa, CO 81101 · last Jun 7, first Sep 15
- Chama, CO 81126 · last May 31, first Sep 23
- Mosca, CO 81146 · last Jun 7, first Sep 15
- San Luis, CO 81152 · last May 31, first Sep 23
- Sanford, CO 81151 · last May 28, first Sep 21
- La Veta, CO 81055 · last May 27, first Sep 25
- Hooper, CO 81136 · last May 24, first Sep 24
Frequently asked questions
- When is the last frost in Blanca, CO?
- For ZIP code 81123, the average last spring frost (32°F) is May 25, based on NOAA 1991-2020 climate normals for the Blanca 4 Nw, CO weather station. There is a 1-in-10 chance of a frost after June 12.
- When is the first frost in Blanca, CO?
- The average first fall frost (32°F) is September 22. There is a 1-in-10 chance of frost by September 10, so tender plants are at risk from that point on.
- How long is the growing season in 81123?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 117 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.