Frost dates in Boulder County, Colorado
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The average last spring frost in Boulder County falls May 6 to Jun 21 and the average first fall frost Sep 2 to Oct 5, depending on the ZIP code (50% odds, 32°F, NOAA 1991–2020 normals). USDA hardiness zone 5b to 6a. Places: Allenspark, Bark Ranch, Boulder, Eldora, Eldorado Springs, Glendale. Pick a ZIP for 10% and 90% odds, soil temperature and the 7-day freeze forecast.
| ZIP | Place | Last spring frost | First fall frost | Zone |
|---|---|---|---|---|
| 80025 | Eldorado Springs | May 24 | Sep 23 | 6a |
| 80026 | Lafayette | May 6 | Oct 5 | 6a |
| 80027 | Louisville | May 6 | Oct 5 | 6a |
| 80301 | Boulder | May 6 | Oct 5 | 6a |
| 80302 | Lazy Acres | May 6 | Oct 5 | 6a |
| 80303 | Boulder | May 6 | Oct 5 | 6a |
| 80304 | Boulder | May 6 | Oct 5 | 6a |
| 80305 | Boulder | May 6 | Oct 5 | 6a |
| 80310 | Boulder | May 6 | Oct 5 | 6a |
| 80455 | Glendale | Jun 21 | Sep 2 | 5b |
| 80466 | Eldora | Jun 21 | Sep 2 | 5b |
| 80471 | Jun 5 | Sep 16 | 5b | |
| 80481 | Bark Ranch | Jun 21 | Sep 2 | 5b |
| 80501 | Longmont | May 7 | Oct 5 | 5b |
| 80503 | Longmont | May 7 | Oct 5 | 6a |
| 80510 | Allenspark | Jun 14 | Sep 12 | 5b |
| 80540 | Lyons | Jun 14 | Sep 12 | 5b |
| 80544 | Niwot | May 7 | Oct 5 | 6a |
Nearby counties
Broomfield County Gilpin County Jefferson County Denver County Adams County Clear Creek County
All Colorado counties · Download Colorado frost dates (CSV)
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