Nashua, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -0.5 °C (low) to 14 °C (high). Annual precipitation averages 350.8 Millimeters. Nashua is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -15.8 °C | -3.8 °C | 8.64 mm |
| February | -13.4 °C | -0.6 °C | 8.64 mm |
| March | -6.8 °C | 6.6 °C | 13.97 mm |
| April | -0.6 °C | 14.9 °C | 23.88 mm |
| May | 5.5 °C | 20.8 °C | 56.39 mm |
| June | 10.8 °C | 25.6 °C | 76.45 mm |
| July | 13.9 °C | 30.6 °C | 49.28 mm |
| August | 12.9 °C | 30.6 °C | 37.08 mm |
| September | 7.2 °C | 24.2 °C | 25.15 mm |
| October | 0.3 °C | 15.1 °C | 24.38 mm |
| November | -7.2 °C | 5.8 °C | 13.97 mm |
| December | -13.3 °C | -1.7 °C | 12.95 mm |
| Annual | -0.5 °C | 14 °C | 350.78 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| 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 |