Frost dates for 80045Aurora, CO
The average last spring frost in Aurora is May 4 and the average first fall frost is October 8, giving a typical growing season of about 156 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 4
- Average first fall frost
- Oct 8
- Growing season
- 156 days
Safer after May 16 (1-in-10 risk)
Possible by Sep 25 (1-in-10 risk)
Last frost typically in 190 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 2 · May 12 · May 26 | Sep 16 · Oct 1 · Oct 13 | 140 days | 100% |
| Frost / freeze (32°F) | Apr 20 · May 4 · May 16 | Sep 25 · Oct 8 · Oct 20 | 156 days | 100% |
| Hard freeze (28°F) | Apr 6 · Apr 22 · May 7 | Oct 3 · Oct 18 · Oct 31 | 177 days | 100% |
Planting calendar for Aurora
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 3 – Jun 9 |
| Tomatoes | Transplant outdoors | May 20 – Jun 18 |
| Peppers | Start seeds indoors | Apr 3 – May 4 |
| Peppers | Transplant outdoors | Jun 3 – Jul 4 |
| Eggplant | Start seeds indoors | Apr 20 – May 19 |
| Eggplant | Transplant outdoors | Jun 3 – Jul 4 |
| Cucumbers | Sow outdoors | Jun 3 – Jun 28 |
| Summer squash | Sow outdoors | May 20 – Jul 4 |
| Winter squash & pumpkins | Sow outdoors | Jun 3 – Jul 4 |
| Snap beans | Sow outdoors | May 20 – Jul 21 |
| Sweet corn | Sow outdoors | May 20 – Jun 18 |
| Watermelon & cantaloupe | Sow outdoors | Jun 3 – Jul 4 |
| Okra | Sow outdoors | May 27 – Jun 19 |
| Peas | Sow outdoors (spring) | Apr 3 – May 19 |
| Potatoes | Plant outdoors (spring) | Apr 3 – Jun 3 |
| Onions | Start seeds indoors (spring) | Feb 20 – Mar 19 |
| Onions | Transplant outdoors (spring) | Apr 20 – May 19 |
| Broccoli | Start seeds indoors (spring) | Mar 16 – Apr 19 |
| Broccoli | Transplant outdoors (spring) | Apr 20 – May 19 |
| Broccoli | Start seeds indoors (fall) | Jun 8 – Jun 18 |
| Broccoli | Transplant outdoors (fall) | Jul 8 – Jul 19 |
| Cabbage | Start seeds indoors (spring) | Mar 6 – Apr 3 |
| Cabbage | Transplant outdoors (spring) | Apr 3 – May 4 |
| Cabbage | Start seeds indoors (fall) | May 29 – Jun 28 |
| Cabbage | Transplant outdoors (fall) | Jun 28 – Jul 29 |
| Leaf lettuce | Sow outdoors (spring) | Apr 3 – Jun 19 |
| Leaf lettuce | Sow outdoors (fall) | Jun 28 – Aug 14 |
| Spinach | Sow outdoors (spring) | Mar 27 – May 10 |
| Spinach | Sow outdoors (fall) | Jul 15 – Aug 19 |
| Radishes | Sow outdoors (spring) | Apr 3 – May 24 |
| Radishes | Sow outdoors (fall) | Jun 28 – Aug 29 |
| Kale | Sow outdoors (spring) | Apr 20 – May 10 |
| Kale | Sow outdoors (fall) | Jun 21 – Jul 29 |
| Carrots | Sow outdoors (spring) | May 4 – Jun 19 |
| Carrots | Sow outdoors (fall) | May 29 – Jul 14 |
| Garlic | Plant outdoors (fall) | Sep 28 – Oct 29 |
Where these dates come from
ZIP code 80045 is matched to the NOAA station Denver-Stapleton, CO, 3.2 km away, at 5,286 ft elevation (91 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Denver-Stapleton, CO (used) | 5,286 ft | May 4 | Oct 8 |
| Cherry Creek Dam, CO | 5,647 ft | May 7 | Oct 8 |
| Denver Water Dept, CO | 5,228 ft | Apr 30 | Oct 12 |
| Denver Intl Ap, CO | 5,414 ft | May 5 | Oct 9 |
Frost dates near Aurora
- Aurora, CO 80040 · last May 4, first Oct 8
- Denver, CO 80201 · last May 4, first Oct 8
- Commerce City, CO 80037 · last May 4, first Oct 8
- Dupont, CO 80024 · last May 4, first Oct 8
- Englewood, CO 80111 · last May 5, first Oct 8
- Henderson, CO 80640 · last May 3, first Oct 7
- Thornton, CO 80241 · last May 2, first Oct 11
- Littleton, CO 80121 · last May 2, first Oct 11
Frequently asked questions
- When is the last frost in Aurora, CO?
- For ZIP code 80045, the average last spring frost (32°F) is May 4, based on NOAA 1991-2020 climate normals for the Denver-Stapleton, CO weather station. There is a 1-in-10 chance of a frost after May 16.
- When is the first frost in Aurora, CO?
- The average first fall frost (32°F) is October 8. There is a 1-in-10 chance of frost by September 25, so tender plants are at risk from that point on.
- How long is the growing season in 80045?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 156 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.