Last spring frost
Jun 16
Frost Dates for Twin Lakes, CO
First fall frost
Sep 10
Growing season
85 days
Hardiness zone
5a
In an average year around Twin Lakes, CO, the last spring frost (32°F) is about Jun 16 and the first fall frost is about Sep 10, giving roughly a 85-day growing season. To be safe most years, wait until Jun 3 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 29 | Jun 16 | Jun 3 |
| Hard (28°F) | Jun 16 | Jun 2 | May 17 |
| Severe (24°F) | Jun 3 | May 16 | May 2 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jun 29 | Jun 25 | Jun 21 | Jun 19 | Jun 16 | Jun 14 | Jun 11 | Jun 8 | Jun 3 |
| 28°F | Jun 16 | Jun 12 | Jun 7 | Jun 4 | Jun 2 | May 31 | May 27 | May 23 | May 17 |
| 24°F | Jun 3 | May 30 | May 23 | May 19 | May 16 | May 13 | May 9 | May 6 | May 2 |
| 20°F | May 18 | May 13 | May 9 | May 6 | May 4 | May 1 | Apr 29 | Apr 25 | Apr 21 |
| 16°F | May 8 | May 4 | May 1 | Apr 28 | Apr 24 | Apr 21 | Apr 18 | Apr 14 | Apr 9 |
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 24 | Sep 10 | Sep 23 |
| Hard (28°F) | Sep 9 | Sep 23 | Oct 4 |
| Severe (24°F) | Sep 20 | Oct 3 | Oct 16 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Aug 24 | Sep 1 | Sep 4 | Sep 7 | Sep 10 | Sep 14 | Sep 17 | Sep 19 | Sep 23 |
| 28°F | Sep 9 | Sep 15 | Sep 18 | Sep 20 | Sep 23 | Sep 25 | Sep 28 | Oct 1 | Oct 4 |
| 24°F | Sep 20 | Sep 25 | Sep 29 | Oct 1 | Oct 3 | Oct 5 | Oct 8 | Oct 12 | Oct 16 |
| 20°F | Sep 30 | Oct 4 | Oct 7 | Oct 10 | Oct 13 | Oct 16 | Oct 19 | Oct 22 | Oct 26 |
| 16°F | Oct 7 | Oct 13 | Oct 17 | Oct 20 | Oct 23 | Oct 26 | Oct 29 | Nov 2 | Nov 6 |
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: Twin Lakes Rsvr, Co, about 5.7 miles away@if(!empty($station['elevation_ft'])), at 9,236 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 Twin Lakes, CO?
On average, the last spring frost (32°F) around Twin Lakes, CO is about Jun 16. In cooler years it can run later, so for a safer bet many gardeners wait until Jun 3.
When is the first frost in the fall?
The first fall frost around Twin Lakes, CO typically arrives about Sep 10. 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 16 on average, or Jun 3 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 85 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 81251 Planting calendar → Colorado frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026