Frost dates for 80648Nunn, CO
The average last spring frost in Nunn is May 13 and the average first fall frost is September 27, giving a typical growing season of about 136 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 13
- Average first fall frost
- Sep 27
- Growing season
- 136 days
Safer after May 27 (1-in-10 risk)
Possible by Sep 14 (1-in-10 risk)
Last frost typically in 198 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 12 · May 25 · Jun 6 | Sep 5 · Sep 19 · Sep 30 | 117 days | 100% |
| Frost / freeze (32°F) | May 2 · May 13 · May 27 | Sep 14 · Sep 27 · Oct 9 | 136 days | 100% |
| Hard freeze (28°F) | Apr 22 · May 4 · May 16 | Sep 24 · Oct 7 · Oct 19 | 156 days | 100% |
Planting calendar for Nunn
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 12 – Jun 18 |
| Tomatoes | Transplant outdoors | May 29 – Jun 7 |
| Peppers | Start seeds indoors | Apr 12 – May 13 |
| Peppers | Transplant outdoors | Jun 12 – Jul 13 |
| Eggplant | Start seeds indoors | Apr 29 – May 28 |
| Eggplant | Transplant outdoors | Jun 12 – Jul 13 |
| Cucumbers | Sow outdoors | Jun 12 – Jun 17 |
| Summer squash | Sow outdoors | May 29 – Jul 13 |
| Winter squash & pumpkins | Sow outdoors | Jun 12 – Jul 13 |
| Snap beans | Sow outdoors | May 29 – Jul 10 |
| Sweet corn | Sow outdoors | May 29 – Jun 7 |
| Watermelon & cantaloupe | Sow outdoors | Jun 12 – Jul 13 |
| Okra | Sow outdoors | Jun 5 – Jun 28 |
| Peas | Sow outdoors (spring) | Apr 12 – May 28 |
| Potatoes | Plant outdoors (spring) | Apr 12 – Jun 12 |
| Onions | Start seeds indoors (spring) | Mar 1 – Mar 28 |
| Onions | Transplant outdoors (spring) | Apr 29 – May 28 |
| Broccoli | Start seeds indoors (spring) | Mar 25 – Apr 28 |
| Broccoli | Transplant outdoors (spring) | Apr 29 – May 28 |
| Broccoli | Start seeds indoors (fall) | May 28 – Jun 7 |
| Broccoli | Transplant outdoors (fall) | Jun 27 – Jul 8 |
| Cabbage | Start seeds indoors (spring) | Mar 15 – Apr 12 |
| Cabbage | Transplant outdoors (spring) | Apr 12 – May 13 |
| Cabbage | Start seeds indoors (fall) | May 18 – Jun 17 |
| Cabbage | Transplant outdoors (fall) | Jun 17 – Jul 18 |
| Leaf lettuce | Sow outdoors (spring) | Apr 12 – Jun 28 |
| Leaf lettuce | Sow outdoors (fall) | Jun 17 – Aug 3 |
| Spinach | Sow outdoors (spring) | Apr 5 – May 19 |
| Spinach | Sow outdoors (fall) | Jul 4 – Aug 8 |
| Radishes | Sow outdoors (spring) | Apr 12 – Jun 2 |
| Radishes | Sow outdoors (fall) | Jun 17 – Aug 18 |
| Kale | Sow outdoors (spring) | Apr 29 – May 19 |
| Kale | Sow outdoors (fall) | Jun 10 – Jul 18 |
| Carrots | Sow outdoors (spring) | May 13 – Jun 28 |
| Carrots | Sow outdoors (fall) | May 18 – Jul 3 |
| Garlic | Plant outdoors (fall) | Sep 17 – Oct 18 |
Where these dates come from
ZIP code 80648 is matched to the NOAA station Nunn 7 Nne, CO, 9.3 km away, at 5,390 ft elevation (137 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Nunn 7 Nne, CO (used) | 5,390 ft | May 13 | Sep 27 |
| Ft Collins 4 E, CO | 4,920 ft | May 3 | Oct 6 |
| Ft Collins, CO | 5,004 ft | May 2 | Oct 7 |
| Greeley Unc, CO | 4,715 ft | May 2 | Oct 8 |
Frost dates near Nunn
- Pierce, CO 80650 · last May 3, first Oct 6
- Ault, CO 80610 · last May 3, first Oct 6
- Carr, CO 80612 · last May 13, first Sep 27
- Wellington, CO 80549 · last May 2, first Oct 7
- Eaton, CO 80615 · last May 2, first Oct 8
- Severance, CO 80546 · last May 3, first Oct 6
- Fort Collins, CO 80522 · last May 2, first Oct 7
- Timnath, CO 80547 · last May 3, first Oct 6
Frequently asked questions
- When is the last frost in Nunn, CO?
- For ZIP code 80648, the average last spring frost (32°F) is May 13, based on NOAA 1991-2020 climate normals for the Nunn 7 Nne, CO weather station. There is a 1-in-10 chance of a frost after May 27.
- When is the first frost in Nunn, CO?
- The average first fall frost (32°F) is September 27. There is a 1-in-10 chance of frost by September 14, so tender plants are at risk from that point on.
- How long is the growing season in 80648?
- 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.