Frost dates for 80422Black Hawk, CO
The average last spring frost in Black Hawk is June 5 and the average first fall frost is September 16, giving a typical growing season of about 103 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Jun 5
- Average first fall frost
- Sep 16
- Growing season
- 103 days
Safer after Jun 19 (1-in-10 risk)
Possible by Sep 2 (1-in-10 risk)
Last frost typically in 221 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 4 · Jun 19 · Jul 3 | Aug 18 · Sep 4 · Sep 17 | 76 days | 100% |
| Frost / freeze (32°F) | May 23 · Jun 5 · Jun 19 | Sep 2 · Sep 16 · Sep 28 | 103 days | 100% |
| Hard freeze (28°F) | May 7 · May 21 · Jun 5 | Sep 11 · Sep 26 · Oct 10 | 126 days | 100% |
Planting calendar for Black Hawk
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 5 – Jul 11 |
| Tomatoes | Transplant outdoors | Jun 21 – May 27 |
| Peppers | Start seeds indoors | May 5 – Jun 5 |
| Peppers | Transplant outdoors | Jul 5 – Aug 5 |
| Eggplant | Start seeds indoors | May 22 – Jun 20 |
| Eggplant | Transplant outdoors | Jul 5 – Aug 5 |
| Cucumbers | Sow outdoors | Jul 5 – Jun 6 |
| Summer squash | Sow outdoors | Jun 21 – Aug 5 |
| Winter squash & pumpkins | Sow outdoors | Jul 5 – Aug 5 |
| Snap beans | Sow outdoors | Jun 21 – Jun 29 |
| Sweet corn | Sow outdoors | Jun 21 – May 27 |
| Watermelon & cantaloupe | Sow outdoors | Jul 5 – Aug 5 |
| Okra | Sow outdoors | Jun 28 – Jul 21 |
| Peas | Sow outdoors (spring) | May 5 – Jun 20 |
| Potatoes | Plant outdoors (spring) | May 5 – Jul 5 |
| Onions | Start seeds indoors (spring) | Mar 24 – Apr 20 |
| Onions | Transplant outdoors (spring) | May 22 – Jun 20 |
| Broccoli | Start seeds indoors (spring) | Apr 17 – May 21 |
| Broccoli | Transplant outdoors (spring) | May 22 – Jun 20 |
| Broccoli | Start seeds indoors (fall) | May 17 – May 27 |
| Broccoli | Transplant outdoors (fall) | Jun 16 – Jun 27 |
| Cabbage | Start seeds indoors (spring) | Apr 7 – May 5 |
| Cabbage | Transplant outdoors (spring) | May 5 – Jun 5 |
| Cabbage | Start seeds indoors (fall) | May 7 – Jun 6 |
| Cabbage | Transplant outdoors (fall) | Jun 6 – Jul 7 |
| Leaf lettuce | Sow outdoors (spring) | May 5 – Jul 21 |
| Leaf lettuce | Sow outdoors (fall) | Jun 6 – Jul 23 |
| Spinach | Sow outdoors (spring) | Apr 28 – Jun 11 |
| Spinach | Sow outdoors (fall) | Jun 23 – Jul 28 |
| Radishes | Sow outdoors (spring) | May 5 – Jun 25 |
| Radishes | Sow outdoors (fall) | Jun 6 – Aug 7 |
| Kale | Sow outdoors (spring) | May 22 – Jun 11 |
| Kale | Sow outdoors (fall) | May 30 – Jul 7 |
| Carrots | Sow outdoors (spring) | Jun 5 – Jul 21 |
| Carrots | Sow outdoors (fall) | May 7 – Jun 22 |
| Garlic | Plant outdoors (fall) | Sep 6 – Oct 7 |
Where these dates come from
ZIP code 80422 is matched to the NOAA station Coal Creek Canyon, CO, 11.8 km away, at 8,951 ft elevation (469 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Coal Creek Canyon, CO (used) | 8,951 ft | Jun 5 | Sep 16 |
| Gross Rsvr, CO | 7,971 ft | May 24 | Sep 23 |
| Ralston Rsvr, CO | 5,900 ft | May 3 | Oct 14 |
| Georgetown, CO | 8,520 ft | May 30 | Sep 19 |
Frost dates near Black Hawk
- Central City, CO 80427 · last May 30, first Sep 19
- Rollinsville, CO 80474 · last —, first —
- Dumont, CO 80436 · last May 24, first Sep 23
- Idaho Springs, CO 80452 · last Jun 6, first Sep 19
- Pinecliffe, CO 80471 · last May 24, first Sep 23
- Golden, CO 80403 · last May 23, first Sep 22
- Nederland, CO 80466 · last May 24, first Sep 23
- Empire, CO 80438 · last May 30, first Sep 19
Frequently asked questions
- When is the last frost in Black Hawk, CO?
- For ZIP code 80422, the average last spring frost (32°F) is June 5, based on NOAA 1991-2020 climate normals for the Coal Creek Canyon, CO weather station. There is a 1-in-10 chance of a frost after June 19.
- When is the first frost in Black Hawk, CO?
- The average first fall frost (32°F) is September 16. There is a 1-in-10 chance of frost by September 2, so tender plants are at risk from that point on.
- How long is the growing season in 80422?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 103 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.