| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F |
| Average First Frost Date: | Oct. 1 - Oct. 10 |
| Average Last Frost Date: | May 11 - May 20 |
| Koppen-Geiger Climate Zone: | Cfa - Humid Subtropical Climate |
| Ecoregion: | 25l - Front Range Fans |
| Heat Zone Days: | 46 - 60 days Over 86°F |
Annual Climate Data for ZIP Code 80021 - Broomfield, CO | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 17 | 20 | 26 | 33 | 42 | 51 | 57 | 55 | 46 | 36 | 25 | 18 | 36 |
| Avg Max Temp (°F) | 44 | 48 | 54 | 61 | 70 | 81 | 87 | 85 | 76 | 66 | 52 | 45 | 64 |
| Avg Precip (In.) | .45 | .4 | 1.15 | 2.05 | 2.42 | 1.67 | 1.66 | 1.52 | 1.07 | .92 | .89 | .53 | 14.73 |