Hays, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 32.1 °F (low) to 55.7 °F (high). Annual precipitation averages 17.3 Inches. Hays 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 | 11.8 °F | 33.0 °F | 0.64 in. |
| February | 14.2 °F | 35.1 °F | 0.55 in. |
| March | 21.5 °F | 44.1 °F | 0.81 in. |
| April | 30.5 °F | 53.5 °F | 1.39 in. |
| May | 39.8 °F | 62.6 °F | 2.99 in. |
| June | 47.8 °F | 71.2 °F | 3.61 in. |
| July | 53.5 °F | 81.8 °F | 2.04 in. |
| August | 52.5 °F | 81.3 °F | 1.29 in. |
| September | 43.3 °F | 70.1 °F | 1.26 in. |
| October | 33.0 °F | 56.4 °F | 1.42 in. |
| November | 22.6 °F | 43.4 °F | 0.65 in. |
| December | 14.8 °F | 35.7 °F | 0.6 in. |
| Annual | 32.1 °F | 55.7 °F | 17.25 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 |