Frost dates for 80439Evergreen, CO
The average last spring frost in Evergreen is May 23 and the average first fall frost is September 22, giving a typical growing season of about 118 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 23
- Average first fall frost
- Sep 22
- Growing season
- 118 days
Safer after Jun 10 (1-in-10 risk)
Possible by Sep 6 (1-in-10 risk)
Last frost typically in 208 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 29 · Jun 10 · Jun 26 | Aug 27 · Sep 11 · Sep 23 | 90 days | 100% |
| Frost / freeze (32°F) | May 9 · May 23 · Jun 10 | Sep 6 · Sep 22 · Oct 3 | 118 days | 100% |
| Hard freeze (28°F) | Apr 29 · May 9 · May 22 | Sep 18 · Oct 2 · Oct 15 | 145 days | 100% |
Planting calendar for Evergreen
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 22 – Jun 28 |
| Tomatoes | Transplant outdoors | Jun 8 – Jun 2 |
| Peppers | Start seeds indoors | Apr 22 – May 23 |
| Peppers | Transplant outdoors | Jun 22 – Jul 23 |
| Eggplant | Start seeds indoors | May 9 – Jun 7 |
| Eggplant | Transplant outdoors | Jun 22 – Jul 23 |
| Cucumbers | Sow outdoors | Jun 22 – Jun 12 |
| Summer squash | Sow outdoors | Jun 8 – Jul 23 |
| Winter squash & pumpkins | Sow outdoors | Jun 22 – Jul 23 |
| Snap beans | Sow outdoors | Jun 8 – Jul 5 |
| Sweet corn | Sow outdoors | Jun 8 – Jun 2 |
| Watermelon & cantaloupe | Sow outdoors | Jun 22 – Jul 23 |
| Okra | Sow outdoors | Jun 15 – Jul 8 |
| Peas | Sow outdoors (spring) | Apr 22 – Jun 7 |
| Potatoes | Plant outdoors (spring) | Apr 22 – Jun 22 |
| Onions | Start seeds indoors (spring) | Mar 11 – Apr 7 |
| Onions | Transplant outdoors (spring) | May 9 – Jun 7 |
| Broccoli | Start seeds indoors (spring) | Apr 4 – May 8 |
| Broccoli | Transplant outdoors (spring) | May 9 – Jun 7 |
| Broccoli | Start seeds indoors (fall) | May 23 – Jun 2 |
| Broccoli | Transplant outdoors (fall) | Jun 22 – Jul 3 |
| Cabbage | Start seeds indoors (spring) | Mar 25 – Apr 22 |
| Cabbage | Transplant outdoors (spring) | Apr 22 – May 23 |
| Cabbage | Start seeds indoors (fall) | May 13 – Jun 12 |
| Cabbage | Transplant outdoors (fall) | Jun 12 – Jul 13 |
| Leaf lettuce | Sow outdoors (spring) | Apr 22 – Jul 8 |
| Leaf lettuce | Sow outdoors (fall) | Jun 12 – Jul 29 |
| Spinach | Sow outdoors (spring) | Apr 15 – May 29 |
| Spinach | Sow outdoors (fall) | Jun 29 – Aug 3 |
| Radishes | Sow outdoors (spring) | Apr 22 – Jun 12 |
| Radishes | Sow outdoors (fall) | Jun 12 – Aug 13 |
| Kale | Sow outdoors (spring) | May 9 – May 29 |
| Kale | Sow outdoors (fall) | Jun 5 – Jul 13 |
| Carrots | Sow outdoors (spring) | May 23 – Jul 8 |
| Carrots | Sow outdoors (fall) | May 13 – Jun 28 |
| Garlic | Plant outdoors (fall) | Sep 12 – Oct 13 |
Where these dates come from
ZIP code 80439 is matched to the NOAA station Evergreen, CO, 2.2 km away, at 6,985 ft elevation (358 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Evergreen, CO (used) | 6,985 ft | May 23 | Sep 22 |
| Lakewood, CO | 5,640 ft | May 3 | Oct 7 |
| Ralston Rsvr, CO | 5,900 ft | May 3 | Oct 14 |
| Marston Fltr Plt, CO | 5,610 ft | May 2 | Oct 11 |
Frost dates near Evergreen
- Kittredge, CO 80457 · last May 23, first Sep 22
- Indian Hills, CO 80454 · last May 23, first Sep 22
- Idledale, CO 80453 · last May 23, first Sep 22
- Conifer, CO 80433 · last Jun 15, first Sep 9
- Morrison, CO 80465 · last May 16, first Oct 1
- Littleton, CO 80162 · last Jun 16, first Sep 8
- Golden, CO 80419 · last Jun 16, first Sep 8
- Evergreen, CO 80437 · last Jun 16, first Sep 8
Frequently asked questions
- When is the last frost in Evergreen, CO?
- For ZIP code 80439, the average last spring frost (32°F) is May 23, based on NOAA 1991-2020 climate normals for the Evergreen, CO weather station. There is a 1-in-10 chance of a frost after June 10.
- When is the first frost in Evergreen, CO?
- The average first fall frost (32°F) is September 22. There is a 1-in-10 chance of frost by September 6, so tender plants are at risk from that point on.
- How long is the growing season in 80439?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 118 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.