Broomfield, Colorado has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 3 °C (low) to 18.4 °C (high). Annual precipitation averages 427 Millimeters. Broomfield is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.7 °C | 7.8 °C | 14.48 mm |
| February | -6.1 °C | 8.3 °C | 17.53 mm |
| March | -2 °C | 13.2 °C | 39.62 mm |
| April | 1.4 °C | 16.4 °C | 59.44 mm |
| May | 6.4 °C | 21.3 °C | 66.55 mm |
| June | 11.6 °C | 28.1 °C | 38.61 mm |
| July | 15.1 °C | 31.6 °C | 46.48 mm |
| August | 13.9 °C | 30.3 °C | 40.64 mm |
| September | 9.3 °C | 25.9 °C | 35.05 mm |
| October | 2.7 °C | 18.7 °C | 32.51 mm |
| November | -2.6 °C | 12.2 °C | 21.34 mm |
| December | -6.8 °C | 7.4 °C | 14.73 mm |
| Annual | 3 °C | 18.4 °C | 426.98 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |