Bruneau, Idaho has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 39.6 °F (low) to 66.6 °F (high). Annual precipitation averages 7.5 Inches. Bruneau is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 24.9 °F | 40.8 °F | 0.93 in. |
| February | 27.4 °F | 48.0 °F | 0.53 in. |
| March | 32.9 °F | 57.6 °F | 0.79 in. |
| April | 37.6 °F | 65.2 °F | 0.8 in. |
| May | 45.3 °F | 74.3 °F | 1.09 in. |
| June | 52.1 °F | 83.3 °F | 0.64 in. |
| July | 59.2 °F | 94.1 °F | 0.1 in. |
| August | 56.8 °F | 92.6 °F | 0.1 in. |
| September | 47.8 °F | 82.4 °F | 0.28 in. |
| October | 37.7 °F | 68.1 °F | 0.62 in. |
| November | 29.3 °F | 51.6 °F | 0.74 in. |
| December | 24.3 °F | 40.6 °F | 0.88 in. |
| Annual | 39.6 °F | 66.6 °F | 7.5 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |