Frost dates for 81120Antonito, CO
The average last spring frost in Antonito is May 28 and the average first fall frost is September 21, giving a typical growing season of about 115 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 28
- Average first fall frost
- Sep 21
- Growing season
- 115 days
Safer after Jun 11 (1-in-10 risk)
Possible by Sep 9 (1-in-10 risk)
Last frost typically in 213 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 27 · Jun 10 · Jun 26 | Aug 30 · Sep 11 · Sep 23 | 92 days | 100% |
| Frost / freeze (32°F) | May 13 · May 28 · Jun 11 | Sep 9 · Sep 21 · Oct 1 | 115 days | 100% |
| Hard freeze (28°F) | Apr 30 · May 13 · Jun 2 | Sep 18 · Sep 29 · Oct 9 | 137 days | 100% |
Planting calendar for Antonito
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 27 – Jul 3 |
| Tomatoes | Transplant outdoors | Jun 13 – Jun 1 |
| Peppers | Start seeds indoors | Apr 27 – May 28 |
| Peppers | Transplant outdoors | Jun 27 – Jul 28 |
| Eggplant | Start seeds indoors | May 14 – Jun 12 |
| Eggplant | Transplant outdoors | Jun 27 – Jul 28 |
| Cucumbers | Sow outdoors | Jun 27 – Jun 11 |
| Summer squash | Sow outdoors | Jun 13 – Jul 28 |
| Winter squash & pumpkins | Sow outdoors | Jun 27 – Jul 28 |
| Snap beans | Sow outdoors | Jun 13 – Jul 4 |
| Sweet corn | Sow outdoors | Jun 13 – Jun 1 |
| Watermelon & cantaloupe | Sow outdoors | Jun 27 – Jul 28 |
| Okra | Sow outdoors | Jun 20 – Jul 13 |
| Peas | Sow outdoors (spring) | Apr 27 – Jun 12 |
| Potatoes | Plant outdoors (spring) | Apr 27 – Jun 27 |
| Onions | Start seeds indoors (spring) | Mar 16 – Apr 12 |
| Onions | Transplant outdoors (spring) | May 14 – Jun 12 |
| Broccoli | Start seeds indoors (spring) | Apr 9 – May 13 |
| Broccoli | Transplant outdoors (spring) | May 14 – Jun 12 |
| Broccoli | Start seeds indoors (fall) | May 22 – Jun 1 |
| Broccoli | Transplant outdoors (fall) | Jun 21 – Jul 2 |
| Cabbage | Start seeds indoors (spring) | Mar 30 – Apr 27 |
| Cabbage | Transplant outdoors (spring) | Apr 27 – May 28 |
| Cabbage | Start seeds indoors (fall) | May 12 – Jun 11 |
| Cabbage | Transplant outdoors (fall) | Jun 11 – Jul 12 |
| Leaf lettuce | Sow outdoors (spring) | Apr 27 – Jul 13 |
| Leaf lettuce | Sow outdoors (fall) | Jun 11 – Jul 28 |
| Spinach | Sow outdoors (spring) | Apr 20 – Jun 3 |
| Spinach | Sow outdoors (fall) | Jun 28 – Aug 2 |
| Radishes | Sow outdoors (spring) | Apr 27 – Jun 17 |
| Radishes | Sow outdoors (fall) | Jun 11 – Aug 12 |
| Kale | Sow outdoors (spring) | May 14 – Jun 3 |
| Kale | Sow outdoors (fall) | Jun 4 – Jul 12 |
| Carrots | Sow outdoors (spring) | May 28 – Jul 13 |
| Carrots | Sow outdoors (fall) | May 12 – Jun 27 |
| Garlic | Plant outdoors (fall) | Sep 11 – Oct 12 |
Where these dates come from
ZIP code 81120 is matched to the NOAA station Manassa, CO, 12.9 km away, at 7,695 ft elevation (235 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Manassa, CO (used) | 7,695 ft | May 28 | Sep 21 |
| Waverly 1W, CO | 7,603 ft | Jun 6 | Sep 15 |
| Alamosa San Luis Ap, CO | 7,534 ft | Jun 7 | Sep 15 |
| Alamosa 1E, CO | 7,540 ft | May 30 | Sep 17 |
Frost dates near Antonito
- Conejos, CO 81129 · last May 28, first Sep 21
- Romeo, CO 81148 · last May 28, first Sep 21
- Manassa, CO 81141 · last May 28, first Sep 21
- Sanford, CO 81151 · last May 28, first Sep 21
- La Jara, CO 81140 · last Jun 6, first Sep 15
- Capulin, CO 81124 · last May 28, first Sep 21
- Costilla, NM 87524 · last Jun 19, first Sep 7
- Jaroso, CO 81138 · last May 31, first Sep 26
Frequently asked questions
- When is the last frost in Antonito, CO?
- For ZIP code 81120, the average last spring frost (32°F) is May 28, based on NOAA 1991-2020 climate normals for the Manassa, CO weather station. There is a 1-in-10 chance of a frost after June 11.
- When is the first frost in Antonito, CO?
- The average first fall frost (32°F) is September 21. There is a 1-in-10 chance of frost by September 9, so tender plants are at risk from that point on.
- How long is the growing season in 81120?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 115 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.