Glen, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -1.9 °C (low) to 14.2 °C (high). Annual precipitation averages 229.1 Millimeters. 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 | -11 °C | 1.7 °C | 5.84 mm |
| February | -9.9 °C | 3.6 °C | 6.35 mm |
| March | -6.1 °C | 8.2 °C | 12.7 mm |
| April | -2.3 °C | 12.9 °C | 21.34 mm |
| May | 2.1 °C | 18.2 °C | 41.91 mm |
| June | 5.7 °C | 22.8 °C | 47.5 mm |
| July | 8.3 °C | 29.1 °C | 21.84 mm |
| August | 7.1 °C | 28.5 °C | 19.3 mm |
| September | 3.2 °C | 22.7 °C | 20.07 mm |
| October | -1.8 °C | 14.9 °C | 15.24 mm |
| November | -7.1 °C | 6.6 °C | 9.65 mm |
| December | -11.5 °C | 1.1 °C | 7.37 mm |
| Annual | -1.9 °C | 14.2 °C | 229.11 mm |
| 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 : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |