Sidney, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 31.1 °F (low) to 55.9 °F (high). Annual precipitation averages 15.4 Inches. Sidney is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 4.8 °F | 24.9 °F | 0.46 in. |
| February | 8.3 °F | 29.6 °F | 0.35 in. |
| March | 19.0 °F | 42.3 °F | 0.63 in. |
| April | 30.6 °F | 57.2 °F | 1.19 in. |
| May | 41.6 °F | 67.9 °F | 2.27 in. |
| June | 51.7 °F | 76.7 °F | 2.74 in. |
| July | 57.0 °F | 84.9 °F | 2.58 in. |
| August | 54.3 °F | 84.6 °F | 1.49 in. |
| September | 44.4 °F | 74.3 °F | 1.5 in. |
| October | 32.7 °F | 57.8 °F | 1.12 in. |
| November | 19.7 °F | 41.3 °F | 0.55 in. |
| December | 9.4 °F | 28.7 °F | 0.49 in. |
| Annual | 31.1 °F | 55.9 °F | 15.37 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4a : -30°F to -25°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |