Montana City, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.4 °C (low) to 13.7 °C (high). Annual precipitation averages 360.9 Millimeters. Montana City is located in USDA Plant Hardiness Zone 5a. 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 | -9.9 °C | 0.9 °C | 14.22 mm |
| February | -8.8 °C | 2.8 °C | 17.02 mm |
| March | -5.2 °C | 7.8 °C | 18.8 mm |
| April | -1.2 °C | 12.6 °C | 38.61 mm |
| May | 3.4 °C | 17.8 °C | 59.44 mm |
| June | 7.2 °C | 22.6 °C | 62.23 mm |
| July | 10.3 °C | 28.8 °C | 30.73 mm |
| August | 9.2 °C | 28.4 °C | 29.21 mm |
| September | 5.3 °C | 22.1 °C | 31.24 mm |
| October | -0.1 °C | 13.7 °C | 27.18 mm |
| November | -5.1 °C | 5.9 °C | 18.8 mm |
| December | -9.6 °C | 0.8 °C | 13.46 mm |
| Annual | -0.4 °C | 13.7 °C | 360.94 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 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |