Winnett, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 32.6 °F (low) to 59.6 °F (high). Annual precipitation averages 13.8 Inches. Winnett is located in USDA Plant Hardiness Zone 4b. 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 | 11.5 °F | 34.5 °F | 0.46 in. |
| February | 14.1 °F | 37.8 °F | 0.39 in. |
| March | 22.6 °F | 47.9 °F | 0.59 in. |
| April | 31.4 °F | 58.3 °F | 1.39 in. |
| May | 40.8 °F | 67.4 °F | 2.61 in. |
| June | 49.5 °F | 76.3 °F | 2.55 in. |
| July | 55.8 °F | 87.1 °F | 1.47 in. |
| August | 53.7 °F | 86.6 °F | 1.31 in. |
| September | 44.1 °F | 75.5 °F | 1.03 in. |
| October | 33.1 °F | 60.6 °F | 1.13 in. |
| November | 22.0 °F | 46.4 °F | 0.42 in. |
| December | 13.1 °F | 36.2 °F | 0.45 in. |
| Annual | 32.6 °F | 59.6 °F | 13.8 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 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |