Niwot, Colorado has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2 °C (low) to 18.6 °C (high). Annual precipitation averages 398.5 Millimeters. Niwot is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.6 °C | 7.2 °C | 11.68 mm |
| February | -7.3 °C | 8 °C | 14.22 mm |
| March | -2.9 °C | 13.5 °C | 35.56 mm |
| April | 0.7 °C | 16.9 °C | 52.83 mm |
| May | 6 °C | 21.7 °C | 66.8 mm |
| June | 10.9 °C | 28.6 °C | 40.39 mm |
| July | 14.3 °C | 32 °C | 39.37 mm |
| August | 13.1 °C | 30.8 °C | 41.15 mm |
| September | 8.4 °C | 26.3 °C | 34.8 mm |
| October | 1.8 °C | 18.9 °C | 30.23 mm |
| November | -3.9 °C | 12 °C | 18.8 mm |
| December | -8.5 °C | 6.8 °C | 12.7 mm |
| Annual | 2 °C | 18.6 °C | 398.53 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |