Klein, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 0.6 °C (low) to 15.9 °C (high). Annual precipitation averages 397 Millimeters. Klein is located in USDA Plant Hardiness Zone 4b. 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 | -10 °C | 2.8 °C | 12.19 mm |
| February | -8.9 °C | 4.4 °C | 12.19 mm |
| March | -4.8 °C | 9.8 °C | 21.08 mm |
| April | -0.4 °C | 14.8 °C | 46.23 mm |
| May | 4.8 °C | 20 °C | 69.85 mm |
| June | 9.4 °C | 25.1 °C | 75.95 mm |
| July | 12.8 °C | 31.3 °C | 44.7 mm |
| August | 11.8 °C | 30.3 °C | 25.15 mm |
| September | 6.4 °C | 24.4 °C | 30.73 mm |
| October | 0.6 °C | 16.3 °C | 33.53 mm |
| November | -5.2 °C | 8.4 °C | 13.72 mm |
| December | -9.5 °C | 3 °C | 11.68 mm |
| Annual | 0.6 °C | 15.9 °C | 397 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 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |