Caldwell, Idaho has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 39.1 °F (low) to 64.8 °F (high). Annual precipitation averages 11 Inches. Caldwell is located in USDA Plant Hardiness Zone 7a. 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 | 23.8 °F | 38.1 °F | 1.6 in. |
| February | 26.8 °F | 46.2 °F | 0.96 in. |
| March | 32.2 °F | 56.7 °F | 1.17 in. |
| April | 36.9 °F | 64.0 °F | 1.09 in. |
| May | 45.2 °F | 73.2 °F | 1.18 in. |
| June | 51.9 °F | 81.7 °F | 0.64 in. |
| July | 58.4 °F | 92.3 °F | 0.27 in. |
| August | 56.2 °F | 91.0 °F | 0.19 in. |
| September | 47.4 °F | 80.6 °F | 0.43 in. |
| October | 37.2 °F | 66.0 °F | 0.77 in. |
| November | 28.9 °F | 49.4 °F | 0.99 in. |
| December | 23.8 °F | 38.8 °F | 1.69 in. |
| Annual | 39.1 °F | 64.8 °F | 10.98 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |