Frost dates for 81220Cimarron, CO
The average last spring frost in Cimarron is June 9 and the average first fall frost is September 16, giving a typical growing season of about 96 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Jun 9
- Average first fall frost
- Sep 16
- Growing season
- 96 days
Safer after Jun 24 (1-in-10 risk)
Possible by Sep 3 (1-in-10 risk)
Last frost typically in 225 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) | — | — | 69 days | 100% |
| Frost / freeze (32°F) | May 26 · Jun 9 · Jun 24 | Sep 3 · Sep 16 · Sep 27 | 96 days | 100% |
| Hard freeze (28°F) | May 11 · May 25 · Jun 7 | Sep 15 · Sep 27 · Oct 7 | 122 days | 100% |
Planting calendar for Cimarron
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 | May 9 – Jul 15 |
| Tomatoes | Transplant outdoors | Jun 25 – May 27 |
| Peppers | Start seeds indoors | May 9 – Jun 9 |
| Peppers | Transplant outdoors | Jul 9 – Aug 9 |
| Eggplant | Start seeds indoors | May 26 – Jun 24 |
| Eggplant | Transplant outdoors | Jul 9 – Aug 9 |
| Cucumbers | Sow outdoors | Jul 9 – Jun 6 |
| Summer squash | Sow outdoors | Jun 25 – Aug 9 |
| Winter squash & pumpkins | Sow outdoors | Jul 9 – Aug 9 |
| Snap beans | Sow outdoors | Jun 25 – Jun 29 |
| Sweet corn | Sow outdoors | Jun 25 – May 27 |
| Watermelon & cantaloupe | Sow outdoors | Jul 9 – Aug 9 |
| Okra | Sow outdoors | Jul 2 – Jul 25 |
| Peas | Sow outdoors (spring) | May 9 – Jun 24 |
| Potatoes | Plant outdoors (spring) | May 9 – Jul 9 |
| Onions | Start seeds indoors (spring) | Mar 28 – Apr 24 |
| Onions | Transplant outdoors (spring) | May 26 – Jun 24 |
| Broccoli | Start seeds indoors (spring) | Apr 21 – May 25 |
| Broccoli | Transplant outdoors (spring) | May 26 – Jun 24 |
| Broccoli | Start seeds indoors (fall) | May 17 – May 27 |
| Broccoli | Transplant outdoors (fall) | Jun 16 – Jun 27 |
| Cabbage | Start seeds indoors (spring) | Apr 11 – May 9 |
| Cabbage | Transplant outdoors (spring) | May 9 – Jun 9 |
| Cabbage | Start seeds indoors (fall) | May 7 – Jun 6 |
| Cabbage | Transplant outdoors (fall) | Jun 6 – Jul 7 |
| Leaf lettuce | Sow outdoors (spring) | May 9 – Jul 25 |
| Leaf lettuce | Sow outdoors (fall) | Jun 6 – Jul 23 |
| Spinach | Sow outdoors (spring) | May 2 – Jun 15 |
| Spinach | Sow outdoors (fall) | Jun 23 – Jul 28 |
| Radishes | Sow outdoors (spring) | May 9 – Jun 29 |
| Radishes | Sow outdoors (fall) | Jun 6 – Aug 7 |
| Kale | Sow outdoors (spring) | May 26 – Jun 15 |
| Kale | Sow outdoors (fall) | May 30 – Jul 7 |
| Carrots | Sow outdoors (spring) | Jun 9 – Jul 25 |
| Carrots | Sow outdoors (fall) | May 7 – Jun 22 |
| Garlic | Plant outdoors (fall) | Sep 6 – Oct 7 |
Where these dates come from
ZIP code 81220 is matched to the NOAA station Blue Mesa Lake, CO, 28.8 km away, at 7,568 ft elevation (119 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Blue Mesa Lake, CO (used) | 7,568 ft | Jun 9 | Sep 16 |
| Cimarron, CO | 6,890 ft | Jun 20 | Sep 10 |
| Montrose 11 Ene, CO | 8,402 ft | May 20 | Oct 1 |
| Black Canyon Of The Gunnison, CO | 8,151 ft | May 23 | Oct 1 |
Frost dates near Cimarron
- Powderhorn, CO 81243 · last Jun 21, first Sep 5
- Montrose, CO 81401 · last Apr 28, first Oct 14
- Crawford, CO 81415 · last Jun 20, first Sep 10
- Ridgway, CO 81432 · last Jun 11, first Sep 13
- Ouray, CO 81427 · last May 17, first Oct 1
- Lake City, CO 81235 · last Jun 15, first Sep 11
- Olathe, CO 81425 · last May 2, first Oct 8
- Lazear, CO 81420 · last May 3, first Oct 12
Frequently asked questions
- When is the last frost in Cimarron, CO?
- For ZIP code 81220, the average last spring frost (32°F) is June 9, based on NOAA 1991-2020 climate normals for the Blue Mesa Lake, CO weather station. There is a 1-in-10 chance of a frost after June 24.
- When is the first frost in Cimarron, CO?
- The average first fall frost (32°F) is September 16. There is a 1-in-10 chance of frost by September 3, so tender plants are at risk from that point on.
- How long is the growing season in 81220?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 96 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.