Basalt, Colorado has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -1.4 °C (low) to 15.9 °C (high). Annual precipitation averages 425.9 Millimeters. Basalt is located in USDA Plant Hardiness Zone 5b. 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 | -12.6 °C | 2.3 °C | 30.73 mm |
| February | -9.5 °C | 4.9 °C | 38.1 mm |
| March | -5.3 °C | 10.3 °C | 22.86 mm |
| April | -1.8 °C | 14.6 °C | 51.05 mm |
| May | 2.2 °C | 19.9 °C | 40.39 mm |
| June | 6.1 °C | 26.4 °C | 27.43 mm |
| July | 9.8 °C | 30.1 °C | 32 mm |
| August | 8.9 °C | 28.7 °C | 42.67 mm |
| September | 4.5 °C | 24.4 °C | 58.42 mm |
| October | -1.2 °C | 17.6 °C | 32 mm |
| November | -6.7 °C | 9.1 °C | 24.64 mm |
| December | -11.6 °C | 2.2 °C | 25.65 mm |
| Annual | -1.4 °C | 15.9 °C | 425.94 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 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 | Exceptional Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |