Frost dates for 80248Denver, CO
The average last spring frost in Denver is April 30 and the average first fall frost is October 12, giving a typical growing season of about 165 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 30
- Average first fall frost
- Oct 12
- Growing season
- 165 days
Safer after May 13 (1-in-10 risk)
Possible by Sep 28 (1-in-10 risk)
Last frost typically in 195 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) | Apr 27 · May 8 · May 25 | Sep 21 · Oct 4 · Oct 16 | 147 days | 100% |
| Frost / freeze (32°F) | Apr 15 · Apr 30 · May 13 | Sep 28 · Oct 12 · Oct 26 | 165 days | 100% |
| Hard freeze (28°F) | Apr 1 · Apr 18 · May 5 | Oct 5 · Oct 21 · Nov 5 | 184 days | 100% |
Planting calendar for Denver
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 | Mar 30 – Jun 5 |
| Tomatoes | Transplant outdoors | May 16 – Jun 22 |
| Peppers | Start seeds indoors | Mar 30 – Apr 30 |
| Peppers | Transplant outdoors | May 30 – Jun 30 |
| Eggplant | Start seeds indoors | Apr 16 – May 15 |
| Eggplant | Transplant outdoors | May 30 – Jun 30 |
| Cucumbers | Sow outdoors | May 30 – Jul 2 |
| Summer squash | Sow outdoors | May 16 – Jun 30 |
| Winter squash & pumpkins | Sow outdoors | May 30 – Jun 30 |
| Snap beans | Sow outdoors | May 16 – Jul 25 |
| Sweet corn | Sow outdoors | May 16 – Jun 22 |
| Watermelon & cantaloupe | Sow outdoors | May 30 – Jun 30 |
| Okra | Sow outdoors | May 23 – Jun 15 |
| Peas | Sow outdoors (spring) | Mar 30 – May 15 |
| Potatoes | Plant outdoors (spring) | Mar 30 – May 30 |
| Onions | Start seeds indoors (spring) | Feb 16 – Mar 15 |
| Onions | Transplant outdoors (spring) | Apr 16 – May 15 |
| Broccoli | Start seeds indoors (spring) | Mar 12 – Apr 15 |
| Broccoli | Transplant outdoors (spring) | Apr 16 – May 15 |
| Broccoli | Start seeds indoors (fall) | Jun 12 – Jun 22 |
| Broccoli | Transplant outdoors (fall) | Jul 12 – Jul 23 |
| Cabbage | Start seeds indoors (spring) | Mar 2 – Mar 30 |
| Cabbage | Transplant outdoors (spring) | Mar 30 – Apr 30 |
| Cabbage | Start seeds indoors (fall) | Jun 2 – Jul 2 |
| Cabbage | Transplant outdoors (fall) | Jul 2 – Aug 2 |
| Leaf lettuce | Sow outdoors (spring) | Mar 30 – Jun 15 |
| Leaf lettuce | Sow outdoors (fall) | Jul 2 – Aug 18 |
| Spinach | Sow outdoors (spring) | Mar 23 – May 6 |
| Spinach | Sow outdoors (fall) | Jul 19 – Aug 23 |
| Radishes | Sow outdoors (spring) | Mar 30 – May 20 |
| Radishes | Sow outdoors (fall) | Jul 2 – Sep 2 |
| Kale | Sow outdoors (spring) | Apr 16 – May 6 |
| Kale | Sow outdoors (fall) | Jun 25 – Aug 2 |
| Carrots | Sow outdoors (spring) | Apr 30 – Jun 15 |
| Carrots | Sow outdoors (fall) | Jun 2 – Jul 18 |
| Garlic | Plant outdoors (fall) | Oct 2 – Nov 2 |
Where these dates come from
ZIP code 80248 is matched to the NOAA station Denver Water Dept, CO, 2.3 km away, at 5,228 ft elevation (48 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Denver Water Dept, CO (used) | 5,228 ft | Apr 30 | Oct 12 |
| Denver-Stapleton, CO | 5,286 ft | May 4 | Oct 8 |
| Lakewood, CO | 5,640 ft | May 3 | Oct 7 |
| Wheat Ridge 2, CO | 5,398 ft | May 5 | Oct 5 |
Frost dates near Denver
- Denver, CO 80208 · last Apr 30, first Oct 12
- Wheat Ridge, CO 80034 · last May 5, first Oct 5
- Commerce City, CO 80037 · last May 4, first Oct 8
- Englewood, CO 80150 · last Apr 30, first Oct 12
- Aurora, CO 80010 · last May 4, first Oct 8
- Westminster, CO 80030 · last May 2, first Oct 11
- Arvada, CO 80001 · last May 5, first Oct 5
- Dupont, CO 80024 · last May 4, first Oct 8
Frequently asked questions
- When is the last frost in Denver, CO?
- For ZIP code 80248, the average last spring frost (32°F) is April 30, based on NOAA 1991-2020 climate normals for the Denver Water Dept, CO weather station. There is a 1-in-10 chance of a frost after May 13.
- When is the first frost in Denver, CO?
- The average first fall frost (32°F) is October 12. There is a 1-in-10 chance of frost by September 28, so tender plants are at risk from that point on.
- How long is the growing season in 80248?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 165 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.