Yaak, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -2 °C (low) to 13 °C (high). Annual precipitation averages 660.4 Millimeters. Yaak is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.4 °C | -0.8 °C | 72.39 mm |
| February | -9.6 °C | 3.1 °C | 50.8 mm |
| March | -5.8 °C | 7.8 °C | 63.75 mm |
| April | -2.9 °C | 12.9 °C | 41.66 mm |
| May | 1.2 °C | 18.8 °C | 56.39 mm |
| June | 4.7 °C | 22.2 °C | 63.75 mm |
| July | 6.6 °C | 28 °C | 28.45 mm |
| August | 5.8 °C | 28.1 °C | 20.57 mm |
| September | 2 °C | 21.8 °C | 36.32 mm |
| October | -2.1 °C | 12.5 °C | 63.25 mm |
| November | -5.4 °C | 3.4 °C | 81.28 mm |
| December | -8.9 °C | -1.6 °C | 81.79 mm |
| Annual | -2 °C | 13 °C | 660.4 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |