Last frost date in Castle Rock, Colorado
May 9
Average last frost in spring. In an early year (1 in 10) it's over by April 30; in a late year (1 in 10) it comes after May 24.
October 2
Average first frost in fall. 1 year in 10 it comes by September 17.
Source: NOAA U.S. Climate Normals 1991–2020, station Castle Rock (USC00051401), 3.7 miles from Castle Rock, elevation 6,185 ft. NOAA National Centers for Environmental Information. These are long-term averages, not a forecast.
This station is also the nearest one for Castle Pines, so its frost dates are the same as Castle Rock's.
| Early year | Average | Late year | |
|---|---|---|---|
| Last frost in spring | Apr 30 | May 9 | May 24 |
| First frost in fall | Sept 17 | Oct 2 | Oct 16 |
Frost-free days in an average year: 143
| Chance in a year | Average last in spring | Average first in fall | |
|---|---|---|---|
| Light frost (36°F) | Every year | May 21 | Sept 25 |
| Frost (32°F) | Every year | May 9 | Oct 2 |
| Hard freeze (28°F) | Every year | May 1 | Oct 12 |
Nights at 32°F or colder in an average year: 167
What to plant now in Castle Rock
- Spring planting calendar for an average last frost around May 10 Castle Rock: May 9
- Fall planting calendar for an average first frost around September 30 Castle Rock: October 2
Planting dates: USDA Home and Garden Bulletin No. 9 (1967), “Suburban and Farm Vegetable Gardens,” tables 4 and 5. How we match the table.
Nearby in Colorado
- Parker 10 mi · last frost May 9
- Centennial 15 mi · last frost May 5
- Littleton 17 mi · last frost May 2
- Monument 21 mi · last frost May 17
- Aurora 24 mi · last frost May 7
Updated