Troy, Idaho has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 2.7 °C (low) to 14.9 °C (high). Annual precipitation averages 736.3 Millimeters. Troy is located in USDA Plant Hardiness Zone 6b. 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 | -3.3 °C | 2.8 °C | 86.36 mm |
| February | -2.9 °C | 5.1 °C | 76.96 mm |
| March | -0.9 °C | 9.2 °C | 71.88 mm |
| April | 1.8 °C | 13.8 °C | 71.37 mm |
| May | 5.3 °C | 19 °C | 59.94 mm |
| June | 7.9 °C | 22.3 °C | 43.43 mm |
| July | 9.8 °C | 28.7 °C | 16.26 mm |
| August | 9.6 °C | 29.3 °C | 18.03 mm |
| September | 6.3 °C | 23.9 °C | 29.72 mm |
| October | 2.6 °C | 15.3 °C | 66.8 mm |
| November | -0.7 °C | 6.8 °C | 90.17 mm |
| December | -3.7 °C | 2.2 °C | 105.41 mm |
| Annual | 2.7 °C | 14.9 °C | 736.33 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 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 | Severe Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |