Frost dates for 80526Fort Collins, CO
The average last spring frost in Fort Collins is May 2 and the average first fall frost is October 7, giving a typical growing season of about 157 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 2
- Average first fall frost
- Oct 7
- Growing season
- 157 days
Safer after May 14 (1-in-10 risk)
Possible by Sep 24 (1-in-10 risk)
Last frost typically in 187 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 1 · May 12 · May 26 | Sep 15 · Sep 29 · Oct 11 | 138 days | 100% |
| Frost / freeze (32°F) | Apr 18 · May 2 · May 14 | Sep 24 · Oct 7 · Oct 20 | 157 days | 100% |
| Hard freeze (28°F) | Apr 5 · Apr 20 · May 5 | Oct 2 · Oct 17 · Oct 28 | 179 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 1 – Jun 7 |
| Tomatoes | Transplant outdoors | May 18 – Jun 17 |
| Peppers | Start seeds indoors | Apr 1 – May 2 |
| Peppers | Transplant outdoors | Jun 1 – Jul 2 |
| Eggplant | Start seeds indoors | Apr 18 – May 17 |
| Eggplant | Transplant outdoors | Jun 1 – Jul 2 |
| Cucumbers | Sow outdoors | Jun 1 – Jun 27 |
| Summer squash | Sow outdoors | May 18 – Jul 2 |
| Winter squash & pumpkins | Sow outdoors | Jun 1 – Jul 2 |
| Snap beans | Sow outdoors | May 18 – Jul 20 |
| Sweet corn | Sow outdoors | May 18 – Jun 17 |
| Watermelon & cantaloupe | Sow outdoors | Jun 1 – Jul 2 |
| Okra | Sow outdoors | May 25 – Jun 17 |
| Peas | Sow outdoors (spring) | Apr 1 – May 17 |
| Potatoes | Plant outdoors (spring) | Apr 1 – Jun 1 |
| Onions | Start seeds indoors (spring) | Feb 18 – Mar 17 |
| Onions | Transplant outdoors (spring) | Apr 18 – May 17 |
| Broccoli | Start seeds indoors (spring) | Mar 14 – Apr 17 |
| Broccoli | Transplant outdoors (spring) | Apr 18 – May 17 |
| Broccoli | Start seeds indoors (fall) | Jun 7 – Jun 17 |
| Broccoli | Transplant outdoors (fall) | Jul 7 – Jul 18 |
| Cabbage | Start seeds indoors (spring) | Mar 4 – Apr 1 |
| Cabbage | Transplant outdoors (spring) | Apr 1 – May 2 |
| Cabbage | Start seeds indoors (fall) | May 28 – Jun 27 |
| Cabbage | Transplant outdoors (fall) | Jun 27 – Jul 28 |
| Leaf lettuce | Sow outdoors (spring) | Apr 1 – Jun 17 |
| Leaf lettuce | Sow outdoors (fall) | Jun 27 – Aug 13 |
| Spinach | Sow outdoors (spring) | Mar 25 – May 8 |
| Spinach | Sow outdoors (fall) | Jul 14 – Aug 18 |
| Radishes | Sow outdoors (spring) | Apr 1 – May 22 |
| Radishes | Sow outdoors (fall) | Jun 27 – Aug 28 |
| Kale | Sow outdoors (spring) | Apr 18 – May 8 |
| Kale | Sow outdoors (fall) | Jun 20 – Jul 28 |
| Carrots | Sow outdoors (spring) | May 2 – Jun 17 |
| Carrots | Sow outdoors (fall) | May 28 – Jul 13 |
| Garlic | Plant outdoors (fall) | Sep 27 – Oct 28 |
Where these dates come from
ZIP code 80526 is matched to the NOAA station Ft Collins, CO, 3.7 km away, at 5,004 ft elevation (78 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Ft Collins, CO (used) | 5,004 ft | May 2 | Oct 7 |
| Ft Collins 4 E, CO | 4,920 ft | May 3 | Oct 6 |
| Loveland 2N, CO | 5,080 ft | May 10 | Oct 1 |
| Waterdale, CO | 5,230 ft | May 12 | Oct 1 |
Frost dates near Fort Collins
- Fort Collins, CO 80521 · last May 2, first Oct 7
- Laporte, CO 80535 · last May 2, first Oct 7
- Timnath, CO 80547 · last May 3, first Oct 6
- Masonville, CO 80541 · last May 12, first Oct 1
- Loveland, CO 80538 · last May 10, first Oct 1
- Bellvue, CO 80512 · last May 21, first Sep 29
- Windsor, CO 80550 · last May 3, first Oct 6
- Wellington, CO 80549 · last May 2, first Oct 7
Frequently asked questions
- When is the last frost in Fort Collins, CO?
- For ZIP code 80526, the average last spring frost (32°F) is May 2, based on NOAA 1991-2020 climate normals for the Ft Collins, CO weather station. There is a 1-in-10 chance of a frost after May 14.
- When is the first frost in Fort Collins, CO?
- The average first fall frost (32°F) is October 7. There is a 1-in-10 chance of frost by September 24, so tender plants are at risk from that point on.
- How long is the growing season in 80526?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 157 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.