Glasgow, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -0.6 °C (low) to 13.5 °C (high). Annual precipitation averages 342.1 Millimeters. Glasgow is located in USDA Plant Hardiness Zone 4a. 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 | -15.9 °C | -4.1 °C | 11.43 mm |
| February | -13.8 °C | -1.1 °C | 9.4 mm |
| March | -7.1 °C | 6.2 °C | 14.22 mm |
| April | -0.5 °C | 14.4 °C | 27.43 mm |
| May | 5.6 °C | 20.1 °C | 54.36 mm |
| June | 10.8 °C | 24.9 °C | 71.63 mm |
| July | 13.9 °C | 30.2 °C | 43.69 mm |
| August | 12.8 °C | 29.9 °C | 32 mm |
| September | 7.1 °C | 23.4 °C | 26.67 mm |
| October | 0.1 °C | 14.3 °C | 26.42 mm |
| November | -7.3 °C | 5.3 °C | 13.21 mm |
| December | -13.4 °C | -1.9 °C | 11.68 mm |
| Annual | -0.6 °C | 13.5 °C | 342.14 mm |
| 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 4a : -34.4°C to -31.7°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |