Turtle Lake, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.9 °C (low) to 13.5 °C (high). Annual precipitation averages 507.2 Millimeters. Turtle Lake is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.7 °C | 0.9 °C | 39.62 mm |
| February | -6.4 °C | 2.9 °C | 31.75 mm |
| March | -3.4 °C | 8.2 °C | 35.81 mm |
| April | -0.1 °C | 12.9 °C | 50.29 mm |
| May | 3.9 °C | 18.2 °C | 58.42 mm |
| June | 7.6 °C | 22 °C | 77.22 mm |
| July | 10.3 °C | 28.3 °C | 27.69 mm |
| August | 9.6 °C | 27.9 °C | 21.84 mm |
| September | 5.6 °C | 21.8 °C | 37.34 mm |
| October | 0.7 °C | 13.1 °C | 46.99 mm |
| November | -3.4 °C | 5.2 °C | 39.62 mm |
| December | -6.5 °C | 0.6 °C | 40.64 mm |
| Annual | 0.9 °C | 13.5 °C | 507.23 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |