Hysham, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 33.8 °F (low) to 60.2 °F (high). Annual precipitation averages 14.8 Inches. Hysham is located in USDA Plant Hardiness Zone 4b. 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 | 11.6 °F | 34.0 °F | 0.5 in. |
| February | 14.4 °F | 38.2 °F | 0.54 in. |
| March | 23.4 °F | 49.4 °F | 0.88 in. |
| April | 33.0 °F | 59.8 °F | 1.66 in. |
| May | 42.6 °F | 68.9 °F | 2.22 in. |
| June | 51.8 °F | 78.3 °F | 2.34 in. |
| July | 57.8 °F | 87.5 °F | 1.62 in. |
| August | 55.3 °F | 86.5 °F | 1.12 in. |
| September | 45.6 °F | 75.8 °F | 1.36 in. |
| October | 33.9 °F | 60.7 °F | 1.41 in. |
| November | 22.7 °F | 46.8 °F | 0.6 in. |
| December | 13.7 °F | 35.9 °F | 0.52 in. |
| Annual | 33.8 °F | 60.2 °F | 14.77 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 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 |