Turtle Lake, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 33.7 °F (low) to 56.3 °F (high). Annual precipitation averages 20 Inches. 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 | 19.9 °F | 33.6 °F | 1.56 in. |
| February | 20.4 °F | 37.3 °F | 1.25 in. |
| March | 25.8 °F | 46.8 °F | 1.41 in. |
| April | 31.9 °F | 55.2 °F | 1.98 in. |
| May | 39.1 °F | 64.8 °F | 2.3 in. |
| June | 45.6 °F | 71.6 °F | 3.04 in. |
| July | 50.6 °F | 82.9 °F | 1.09 in. |
| August | 49.2 °F | 82.3 °F | 0.86 in. |
| September | 42.1 °F | 71.2 °F | 1.47 in. |
| October | 33.3 °F | 55.5 °F | 1.85 in. |
| November | 25.9 °F | 41.3 °F | 1.56 in. |
| December | 20.3 °F | 33.0 °F | 1.6 in. |
| Annual | 33.7 °F | 56.3 °F | 19.97 in. |
| 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 : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |