Declo, Idaho has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 34.8 °F (low) to 61.3 °F (high). Annual precipitation averages 10.5 Inches. Declo is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 19.1 °F | 36.4 °F | 1.17 in. |
| February | 22.2 °F | 41.6 °F | 0.71 in. |
| March | 28.1 °F | 51.9 °F | 1.0 in. |
| April | 32.8 °F | 59.1 °F | 1.09 in. |
| May | 40.6 °F | 68.5 °F | 1.48 in. |
| June | 47.3 °F | 77.7 °F | 0.78 in. |
| July | 53.8 °F | 88.1 °F | 0.26 in. |
| August | 51.8 °F | 87.2 °F | 0.45 in. |
| September | 43.6 °F | 77.2 °F | 0.63 in. |
| October | 34.1 °F | 63.2 °F | 0.86 in. |
| November | 25.3 °F | 48.0 °F | 0.87 in. |
| December | 19.2 °F | 36.8 °F | 1.23 in. |
| Annual | 34.8 °F | 61.3 °F | 10.53 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |