Frost dates for 80225Denver, CO
The average last spring frost in Denver is May 3 and the average first fall frost is October 7, giving a typical growing season of about 155 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 3
- Average first fall frost
- Oct 7
- Growing season
- 155 days
Safer after May 18 (1-in-10 risk)
Possible by Sep 24 (1-in-10 risk)
Last frost typically in 184 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 14 · May 29 | Sep 16 · Sep 30 · Oct 12 | 137 days | 100% |
| Frost / freeze (32°F) | Apr 19 · May 3 · May 18 | Sep 24 · Oct 7 · Oct 21 | 155 days | 100% |
| Hard freeze (28°F) | Apr 5 · Apr 22 · May 7 | Oct 1 · Oct 16 · Oct 30 | 176 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 | Apr 2 – Jun 8 |
| Tomatoes | Transplant outdoors | May 19 – Jun 17 |
| 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 27 |
| Summer squash | Sow outdoors | May 19 – Jul 3 |
| Winter squash & pumpkins | Sow outdoors | Jun 2 – Jul 3 |
| Snap beans | Sow outdoors | May 19 – Jul 20 |
| Sweet corn | Sow outdoors | May 19 – Jun 17 |
| 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 7 – Jun 17 |
| Broccoli | Transplant outdoors (fall) | Jul 7 – Jul 18 |
| Cabbage | Start seeds indoors (spring) | Mar 5 – Apr 2 |
| Cabbage | Transplant outdoors (spring) | Apr 2 – May 3 |
| Cabbage | Start seeds indoors (fall) | May 28 – Jun 27 |
| Cabbage | Transplant outdoors (fall) | Jun 27 – Jul 28 |
| Leaf lettuce | Sow outdoors (spring) | Apr 2 – Jun 18 |
| Leaf lettuce | Sow outdoors (fall) | Jun 27 – Aug 13 |
| Spinach | Sow outdoors (spring) | Mar 26 – May 9 |
| Spinach | Sow outdoors (fall) | Jul 14 – Aug 18 |
| Radishes | Sow outdoors (spring) | Apr 2 – May 23 |
| Radishes | Sow outdoors (fall) | Jun 27 – Aug 28 |
| Kale | Sow outdoors (spring) | Apr 19 – May 9 |
| Kale | Sow outdoors (fall) | Jun 20 – Jul 28 |
| Carrots | Sow outdoors (spring) | May 3 – Jun 18 |
| Carrots | Sow outdoors (fall) | May 28 – Jul 13 |
| Garlic | Plant outdoors (fall) | Sep 27 – Oct 28 |
Where these dates come from
ZIP code 80225 is matched to the NOAA station Lakewood, CO, 5.8 km away, at 5,640 ft elevation (42 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Lakewood, CO (used) | 5,640 ft | May 3 | Oct 7 |
| Wheat Ridge 2, CO | 5,398 ft | May 5 | Oct 5 |
| Marston Fltr Plt, CO | 5,610 ft | May 2 | Oct 11 |
| Denver Water Dept, CO | 5,228 ft | Apr 30 | Oct 12 |
Frost dates near Denver
- Denver, CO 80232 · last May 2, first Oct 11
- Golden, CO 80401 · last May 3, first Oct 14
- Wheat Ridge, CO 80034 · last May 5, first Oct 5
- Littleton, CO 80123 · last May 2, first Oct 11
- Morrison, CO 80465 · last May 16, first Oct 1
- Arvada, CO 80002 · last May 5, first Oct 5
- Idledale, CO 80453 · last May 23, first Sep 22
- Englewood, CO 80110 · last Apr 30, first Oct 12
Frequently asked questions
- When is the last frost in Denver, CO?
- For ZIP code 80225, the average last spring frost (32°F) is May 3, based on NOAA 1991-2020 climate normals for the Lakewood, CO weather station. There is a 1-in-10 chance of a frost after May 18.
- When is the first frost in Denver, 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 80225?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 155 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.