Frost dates for 81624Collbran, CO
The average last spring frost in Collbran is May 17 and the average first fall frost is September 30, giving a typical growing season of about 136 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 17
- Average first fall frost
- Sep 30
- Growing season
- 136 days
Safer after Jun 3 (1-in-10 risk)
Possible by Sep 18 (1-in-10 risk)
Last frost typically in 202 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 17 · May 31 · Jun 13 | Sep 10 · Sep 22 · Oct 2 | 113 days | 100% |
| Frost / freeze (32°F) | May 2 · May 17 · Jun 3 | Sep 18 · Sep 30 · Oct 12 | 136 days | 100% |
| Hard freeze (28°F) | Apr 19 · May 3 · May 20 | Sep 27 · Oct 9 · Oct 21 | 159 days | 100% |
Planting calendar for Collbran
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 16 – Jun 22 |
| Tomatoes | Transplant outdoors | Jun 2 – Jun 10 |
| Peppers | Start seeds indoors | Apr 16 – May 17 |
| Peppers | Transplant outdoors | Jun 16 – Jul 17 |
| Eggplant | Start seeds indoors | May 3 – Jun 1 |
| Eggplant | Transplant outdoors | Jun 16 – Jul 17 |
| Cucumbers | Sow outdoors | Jun 16 – Jun 20 |
| Summer squash | Sow outdoors | Jun 2 – Jul 17 |
| Winter squash & pumpkins | Sow outdoors | Jun 16 – Jul 17 |
| Snap beans | Sow outdoors | Jun 2 – Jul 13 |
| Sweet corn | Sow outdoors | Jun 2 – Jun 10 |
| Watermelon & cantaloupe | Sow outdoors | Jun 16 – Jul 17 |
| Okra | Sow outdoors | Jun 9 – Jul 2 |
| Peas | Sow outdoors (spring) | Apr 16 – Jun 1 |
| Potatoes | Plant outdoors (spring) | Apr 16 – Jun 16 |
| Onions | Start seeds indoors (spring) | Mar 5 – Apr 1 |
| Onions | Transplant outdoors (spring) | May 3 – Jun 1 |
| Broccoli | Start seeds indoors (spring) | Mar 29 – May 2 |
| Broccoli | Transplant outdoors (spring) | May 3 – Jun 1 |
| Broccoli | Start seeds indoors (fall) | May 31 – Jun 10 |
| Broccoli | Transplant outdoors (fall) | Jun 30 – Jul 11 |
| Cabbage | Start seeds indoors (spring) | Mar 19 – Apr 16 |
| Cabbage | Transplant outdoors (spring) | Apr 16 – May 17 |
| Cabbage | Start seeds indoors (fall) | May 21 – Jun 20 |
| Cabbage | Transplant outdoors (fall) | Jun 20 – Jul 21 |
| Leaf lettuce | Sow outdoors (spring) | Apr 16 – Jul 2 |
| Leaf lettuce | Sow outdoors (fall) | Jun 20 – Aug 6 |
| Spinach | Sow outdoors (spring) | Apr 9 – May 23 |
| Spinach | Sow outdoors (fall) | Jul 7 – Aug 11 |
| Radishes | Sow outdoors (spring) | Apr 16 – Jun 6 |
| Radishes | Sow outdoors (fall) | Jun 20 – Aug 21 |
| Kale | Sow outdoors (spring) | May 3 – May 23 |
| Kale | Sow outdoors (fall) | Jun 13 – Jul 21 |
| Carrots | Sow outdoors (spring) | May 17 – Jul 2 |
| Carrots | Sow outdoors (fall) | May 21 – Jul 6 |
| Garlic | Plant outdoors (fall) | Sep 20 – Oct 21 |
Where these dates come from
ZIP code 81624 is matched to the NOAA station Collbran 1Wsw, CO, 4.8 km away, at 6,009 ft elevation (513 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Collbran 1Wsw, CO (used) | 6,009 ft | May 17 | Sep 30 |
| Bonham Rsvr, CO | 9,853 ft | — | — |
| Rifle Garfield Co Ap, CO | 5,530 ft | May 11 | Oct 4 |
| Cedaredge 3E, CO | 6,838 ft | May 3 | Oct 9 |
Frost dates near Collbran
- Molina, CO 81646 · last May 17, first Sep 30
- Mesa, CO 81643 · last May 17, first Sep 30
- Battlement Mesa, CO 81636 · last May 11, first Oct 4
- Parachute, CO 81635 · last May 11, first Oct 4
- De Beque, CO 81630 · last Apr 17, first Oct 26
- Rifle, CO 81650 · last May 11, first Oct 4
- Silt, CO 81652 · last May 11, first Oct 4
- Cedaredge, CO 81413 · last May 3, first Oct 9
Frequently asked questions
- When is the last frost in Collbran, CO?
- For ZIP code 81624, the average last spring frost (32°F) is May 17, based on NOAA 1991-2020 climate normals for the Collbran 1Wsw, CO weather station. There is a 1-in-10 chance of a frost after June 3.
- When is the first frost in Collbran, CO?
- The average first fall frost (32°F) is September 30. There is a 1-in-10 chance of frost by September 18, so tender plants are at risk from that point on.
- How long is the growing season in 81624?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 136 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.