Last spring frost
Jun 6
Frost Dates for McCoy, CO
First fall frost
Sep 14
Growing season
98 days
Hardiness zone
5b
In an average year around McCoy, CO, the last spring frost (32°F) is about Jun 6 and the first fall frost is about Sep 14, giving roughly a 98-day growing season. To be safe most years, wait until May 24 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Freeze (32°F) | Jun 23 | Jun 6 | May 24 |
| Hard (28°F) | Jun 5 | May 22 | May 8 |
| Severe (24°F) | May 22 | May 6 | Apr 24 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jun 23 | Jun 17 | Jun 13 | Jun 9 | Jun 6 | Jun 4 | Jun 1 | May 29 | May 24 |
| 28°F | Jun 5 | May 31 | May 28 | May 24 | May 22 | May 19 | May 16 | May 12 | May 8 |
| 24°F | May 22 | May 16 | May 13 | May 9 | May 6 | May 4 | May 1 | Apr 29 | Apr 24 |
| 20°F | May 13 | May 6 | May 2 | Apr 29 | Apr 26 | Apr 23 | Apr 19 | Apr 15 | Apr 9 |
| 16°F | May 5 | Apr 27 | Apr 22 | Apr 17 | Apr 13 | Apr 10 | Apr 7 | Apr 3 | Mar 31 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Freeze (32°F) | Aug 31 | Sep 14 | Sep 26 |
| Hard (28°F) | Sep 9 | Sep 25 | Oct 7 |
| Severe (24°F) | Sep 21 | Oct 6 | Oct 21 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Aug 31 | Sep 5 | Sep 8 | Sep 11 | Sep 14 | Sep 16 | Sep 20 | Sep 23 | Sep 26 |
| 28°F | Sep 9 | Sep 15 | Sep 19 | Sep 23 | Sep 25 | Sep 28 | Oct 1 | Oct 3 | Oct 7 |
| 24°F | Sep 21 | Sep 27 | Oct 1 | Oct 3 | Oct 6 | Oct 9 | Oct 12 | Oct 16 | Oct 21 |
| 20°F | Oct 1 | Oct 6 | Oct 11 | Oct 15 | Oct 17 | Oct 20 | Oct 23 | Oct 26 | Oct 30 |
| 16°F | Oct 10 | Oct 16 | Oct 19 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 3 | Nov 8 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Green Mt Dam, Co, about 12 miles away@if(!empty($station['elevation_ft'])), at 7,740 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in McCoy, CO?
On average, the last spring frost (32°F) around McCoy, CO is about Jun 6. In cooler years it can run later, so for a safer bet many gardeners wait until May 24.
When is the first frost in the fall?
The first fall frost around McCoy, CO typically arrives about Sep 14. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around Jun 6 on average, or May 24 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 98 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 80423 Planting calendar → Colorado frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026