Basalt, Idaho has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 31.8 °F (low) to 58 °F (high). Annual precipitation averages 10.8 Inches. Basalt is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 13.7 °F | 30.4 °F | 0.88 in. |
| February | 16.7 °F | 35.3 °F | 0.62 in. |
| March | 25.8 °F | 47.7 °F | 0.95 in. |
| April | 31.0 °F | 57.5 °F | 1.07 in. |
| May | 38.7 °F | 66.8 °F | 1.56 in. |
| June | 45.2 °F | 75.5 °F | 1.12 in. |
| July | 50.7 °F | 86.0 °F | 0.49 in. |
| August | 49.1 °F | 85.7 °F | 0.6 in. |
| September | 41.5 °F | 75.3 °F | 0.94 in. |
| October | 31.8 °F | 60.4 °F | 1.04 in. |
| November | 22.6 °F | 44.2 °F | 0.71 in. |
| December | 14.5 °F | 31.5 °F | 0.8 in. |
| Annual | 31.8 °F | 58 °F | 10.78 in. |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |