Glen, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 28.5 °F (low) to 57.5 °F (high). Annual precipitation averages 9 Inches. Glen 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.1 - Sep. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.2 °F | 35.0 °F | 0.23 in. |
| February | 14.1 °F | 38.4 °F | 0.25 in. |
| March | 21.1 °F | 46.8 °F | 0.5 in. |
| April | 27.8 °F | 55.3 °F | 0.84 in. |
| May | 35.8 °F | 64.7 °F | 1.65 in. |
| June | 42.3 °F | 73.0 °F | 1.87 in. |
| July | 47.0 °F | 84.4 °F | 0.86 in. |
| August | 44.7 °F | 83.3 °F | 0.76 in. |
| September | 37.7 °F | 72.9 °F | 0.79 in. |
| October | 28.7 °F | 58.8 °F | 0.6 in. |
| November | 19.2 °F | 43.8 °F | 0.38 in. |
| December | 11.3 °F | 33.9 °F | 0.29 in. |
| Annual | 28.5 °F | 57.5 °F | 9.02 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 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |