Troy, Montana has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 2 °C (low) to 15.2 °C (high). Annual precipitation averages 585 Millimeters. Troy is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.9 °C | 1.5 °C | 69.09 mm |
| February | -4.6 °C | 4.6 °C | 46.99 mm |
| March | -2.1 °C | 9.9 °C | 54.86 mm |
| April | 0.8 °C | 15.3 °C | 44.2 mm |
| May | 4.8 °C | 21.1 °C | 47.5 mm |
| June | 8.3 °C | 24.4 °C | 55.12 mm |
| July | 10.4 °C | 30.4 °C | 16 mm |
| August | 9.6 °C | 30.4 °C | 18.29 mm |
| September | 5.9 °C | 24 °C | 26.92 mm |
| October | 1.8 °C | 14.1 °C | 54.36 mm |
| November | -1.4 °C | 5.8 °C | 84.58 mm |
| December | -4.6 °C | 1.2 °C | 67.06 mm |
| Annual | 2 °C | 15.2 °C | 584.97 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |