Frost dates for 80524Fort Collins, CO
The average last spring frost in Fort Collins is May 3 and the average first fall frost is October 6, giving a typical growing season of about 154 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 3
- Average first fall frost
- Oct 6
- Growing season
- 154 days
Safer after May 15 (1-in-10 risk)
Possible by Sep 22 (1-in-10 risk)
Last frost typically in 188 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 3 · May 14 · May 26 | Sep 13 · Sep 27 · Oct 8 | 136 days | 100% |
| Frost / freeze (32°F) | Apr 21 · May 3 · May 15 | Sep 22 · Oct 6 · Oct 17 | 154 days | 100% |
| Hard freeze (28°F) | Apr 8 · Apr 23 · May 8 | Sep 30 · Oct 14 · Oct 26 | 174 days | 100% |
Planting calendar for Fort Collins
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 2 – Jun 8 |
| Tomatoes | Transplant outdoors | May 19 – Jun 16 |
| Peppers | Start seeds indoors | Apr 2 – May 3 |
| Peppers | Transplant outdoors | Jun 2 – Jul 3 |
| Eggplant | Start seeds indoors | Apr 19 – May 18 |
| Eggplant | Transplant outdoors | Jun 2 – Jul 3 |
| Cucumbers | Sow outdoors | Jun 2 – Jun 26 |
| Summer squash | Sow outdoors | May 19 – Jul 3 |
| Winter squash & pumpkins | Sow outdoors | Jun 2 – Jul 3 |
| Snap beans | Sow outdoors | May 19 – Jul 19 |
| Sweet corn | Sow outdoors | May 19 – Jun 16 |
| Watermelon & cantaloupe | Sow outdoors | Jun 2 – Jul 3 |
| Okra | Sow outdoors | May 26 – Jun 18 |
| Peas | Sow outdoors (spring) | Apr 2 – May 18 |
| Potatoes | Plant outdoors (spring) | Apr 2 – Jun 2 |
| Onions | Start seeds indoors (spring) | Feb 19 – Mar 18 |
| Onions | Transplant outdoors (spring) | Apr 19 – May 18 |
| Broccoli | Start seeds indoors (spring) | Mar 15 – Apr 18 |
| Broccoli | Transplant outdoors (spring) | Apr 19 – May 18 |
| Broccoli | Start seeds indoors (fall) | Jun 6 – Jun 16 |
| Broccoli | Transplant outdoors (fall) | Jul 6 – Jul 17 |
| Cabbage | Start seeds indoors (spring) | Mar 5 – Apr 2 |
| Cabbage | Transplant outdoors (spring) | Apr 2 – May 3 |
| Cabbage | Start seeds indoors (fall) | May 27 – Jun 26 |
| Cabbage | Transplant outdoors (fall) | Jun 26 – Jul 27 |
| Leaf lettuce | Sow outdoors (spring) | Apr 2 – Jun 18 |
| Leaf lettuce | Sow outdoors (fall) | Jun 26 – Aug 12 |
| Spinach | Sow outdoors (spring) | Mar 26 – May 9 |
| Spinach | Sow outdoors (fall) | Jul 13 – Aug 17 |
| Radishes | Sow outdoors (spring) | Apr 2 – May 23 |
| Radishes | Sow outdoors (fall) | Jun 26 – Aug 27 |
| Kale | Sow outdoors (spring) | Apr 19 – May 9 |
| Kale | Sow outdoors (fall) | Jun 19 – Jul 27 |
| Carrots | Sow outdoors (spring) | May 3 – Jun 18 |
| Carrots | Sow outdoors (fall) | May 27 – Jul 12 |
| Garlic | Plant outdoors (fall) | Sep 26 – Oct 27 |
Where these dates come from
ZIP code 80524 is matched to the NOAA station Ft Collins 4 E, CO, 3.9 km away, at 4,920 ft elevation (31 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Ft Collins 4 E, CO (used) | 4,920 ft | May 3 | Oct 6 |
| Ft Collins, CO | 5,004 ft | May 2 | Oct 7 |
| Loveland 2N, CO | 5,080 ft | May 10 | Oct 1 |
| Buckhorn Mtn 1 E, CO | 7,400 ft | May 21 | Sep 29 |
Frost dates near Fort Collins
- Fort Collins, CO 80523 · last May 2, first Oct 7
- Laporte, CO 80535 · last May 2, first Oct 7
- Timnath, CO 80547 · last May 3, first Oct 6
- Wellington, CO 80549 · last May 2, first Oct 7
- Bellvue, CO 80512 · last May 21, first Sep 29
- Masonville, CO 80541 · last May 12, first Oct 1
- Windsor, CO 80550 · last May 3, first Oct 6
- Severance, CO 80546 · last May 3, first Oct 6
Frequently asked questions
- When is the last frost in Fort Collins, CO?
- For ZIP code 80524, the average last spring frost (32°F) is May 3, based on NOAA 1991-2020 climate normals for the Ft Collins 4 E, CO weather station. There is a 1-in-10 chance of a frost after May 15.
- When is the first frost in Fort Collins, CO?
- The average first fall frost (32°F) is October 6. There is a 1-in-10 chance of frost by September 22, so tender plants are at risk from that point on.
- How long is the growing season in 80524?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 154 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.