Frost dates for 81639Hayden, CO
The average last spring frost in Hayden is June 1 and the average first fall frost is September 20, giving a typical growing season of about 109 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Jun 1
- Average first fall frost
- Sep 20
- Growing season
- 109 days
Safer after Jun 16 (1-in-10 risk)
Possible by Sep 7 (1-in-10 risk)
Last frost typically in 213 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) | Jun 2 · Jun 17 · Jul 3 | Aug 27 · Sep 10 · Sep 22 | 85 days | 100% |
| Frost / freeze (32°F) | May 15 · Jun 1 · Jun 16 | Sep 7 · Sep 20 · Sep 30 | 109 days | 100% |
| Hard freeze (28°F) | Apr 29 · May 13 · Jun 1 | Sep 16 · Sep 29 · Oct 13 | 138 days | 100% |
Planting calendar for Hayden
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 | May 1 – Jul 7 |
| Tomatoes | Transplant outdoors | Jun 17 – May 31 |
| Peppers | Start seeds indoors | May 1 – Jun 1 |
| Peppers | Transplant outdoors | Jul 1 – Aug 1 |
| Eggplant | Start seeds indoors | May 18 – Jun 16 |
| Eggplant | Transplant outdoors | Jul 1 – Aug 1 |
| Cucumbers | Sow outdoors | Jul 1 – Jun 10 |
| Summer squash | Sow outdoors | Jun 17 – Aug 1 |
| Winter squash & pumpkins | Sow outdoors | Jul 1 – Aug 1 |
| Snap beans | Sow outdoors | Jun 17 – Jul 3 |
| Sweet corn | Sow outdoors | Jun 17 – May 31 |
| Watermelon & cantaloupe | Sow outdoors | Jul 1 – Aug 1 |
| Okra | Sow outdoors | Jun 24 – Jul 17 |
| Peas | Sow outdoors (spring) | May 1 – Jun 16 |
| Potatoes | Plant outdoors (spring) | May 1 – Jul 1 |
| Onions | Start seeds indoors (spring) | Mar 20 – Apr 16 |
| Onions | Transplant outdoors (spring) | May 18 – Jun 16 |
| Broccoli | Start seeds indoors (spring) | Apr 13 – May 17 |
| Broccoli | Transplant outdoors (spring) | May 18 – Jun 16 |
| Broccoli | Start seeds indoors (fall) | May 21 – May 31 |
| Broccoli | Transplant outdoors (fall) | Jun 20 – Jul 1 |
| Cabbage | Start seeds indoors (spring) | Apr 3 – May 1 |
| Cabbage | Transplant outdoors (spring) | May 1 – Jun 1 |
| Cabbage | Start seeds indoors (fall) | May 11 – Jun 10 |
| Cabbage | Transplant outdoors (fall) | Jun 10 – Jul 11 |
| Leaf lettuce | Sow outdoors (spring) | May 1 – Jul 17 |
| Leaf lettuce | Sow outdoors (fall) | Jun 10 – Jul 27 |
| Spinach | Sow outdoors (spring) | Apr 24 – Jun 7 |
| Spinach | Sow outdoors (fall) | Jun 27 – Aug 1 |
| Radishes | Sow outdoors (spring) | May 1 – Jun 21 |
| Radishes | Sow outdoors (fall) | Jun 10 – Aug 11 |
| Kale | Sow outdoors (spring) | May 18 – Jun 7 |
| Kale | Sow outdoors (fall) | Jun 3 – Jul 11 |
| Carrots | Sow outdoors (spring) | Jun 1 – Jul 17 |
| Carrots | Sow outdoors (fall) | May 11 – Jun 26 |
| Garlic | Plant outdoors (fall) | Sep 10 – Oct 11 |
Where these dates come from
ZIP code 81639 is matched to the NOAA station Hayden, CO, 0.3 km away, at 6,467 ft elevation (105 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Hayden, CO (used) | 6,467 ft | Jun 1 | Sep 20 |
| Craig Moffat Co Ap, CO | 6,186 ft | Jun 6 | Sep 12 |
| Craig 4Sw, CO | 6,496 ft | May 29 | Sep 20 |
| Steamboat Springs, CO | 6,866 ft | Jun 9 | Sep 12 |
Frost dates near Hayden
- Craig, CO 81626 · last Jun 6, first Sep 12
- Steamboat Springs, CO 80487 · last Jun 9, first Sep 12
- Hamilton, CO 81638 · last May 29, first Sep 20
- Oak Creek, CO 80467 · last Jun 14, first Sep 11
- Clark, CO 80428 · last Jun 9, first Sep 12
- Phippsburg, CO 80469 · last Jun 14, first Sep 11
- Yampa, CO 80483 · last Jun 14, first Sep 11
- Slater, CO 81653 · last Jun 1, first Sep 18
Frequently asked questions
- When is the last frost in Hayden, CO?
- For ZIP code 81639, the average last spring frost (32°F) is June 1, based on NOAA 1991-2020 climate normals for the Hayden, CO weather station. There is a 1-in-10 chance of a frost after June 16.
- When is the first frost in Hayden, CO?
- The average first fall frost (32°F) is September 20. There is a 1-in-10 chance of frost by September 7, so tender plants are at risk from that point on.
- How long is the growing season in 81639?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 109 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.