Winston, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 31.8 °F (low) to 56.6 °F (high). Annual precipitation averages 13 Inches. Winston is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep.1 - Sep. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 14.9 °F | 34.2 °F | 0.43 in. |
| February | 16.5 °F | 37.3 °F | 0.38 in. |
| March | 23.1 °F | 46.2 °F | 0.67 in. |
| April | 30.1 °F | 54.8 °F | 1.35 in. |
| May | 38.3 °F | 63.9 °F | 2.1 in. |
| June | 45.4 °F | 72.3 °F | 2.52 in. |
| July | 51.3 °F | 82.9 °F | 1.28 in. |
| August | 49.4 °F | 82.3 °F | 1.13 in. |
| September | 42.2 °F | 71.6 °F | 1.1 in. |
| October | 32.4 °F | 57.1 °F | 0.91 in. |
| November | 22.9 °F | 42.5 °F | 0.6 in. |
| December | 15.4 °F | 33.7 °F | 0.48 in. |
| Annual | 31.8 °F | 56.6 °F | 12.95 in. |
| Average First Frost Date | Sep.1 - Sep. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |