Plentywood, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -2.5 °C (low) to 11.6 °C (high). Annual precipitation averages 374.7 Millimeters. Plentywood is located in USDA Plant Hardiness Zone 3b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -18.3 °C | -6.3 °C | 10.92 mm |
| February | -15.5 °C | -3.3 °C | 9.4 mm |
| March | -9.2 °C | 3.3 °C | 16.51 mm |
| April | -2.4 °C | 12.4 °C | 26.92 mm |
| May | 3.9 °C | 19.3 °C | 44.7 mm |
| June | 9.7 °C | 23.8 °C | 80.52 mm |
| July | 12.1 °C | 27.8 °C | 68.07 mm |
| August | 10.8 °C | 28.1 °C | 35.31 mm |
| September | 5.1 °C | 21.9 °C | 32.51 mm |
| October | -1.8 °C | 12.7 °C | 23.88 mm |
| November | -8.9 °C | 2.9 °C | 13.72 mm |
| December | -15.1 °C | -3.8 °C | 12.19 mm |
| Annual | -2.5 °C | 11.6 °C | 374.65 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 3b : -37.2°C to -34.4°C |
| Plant Hardiness Zone - 2012 | Zone 3b : -37.2°C to -34.4°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |