Libby, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 34.2 °F (low) to 58.9 °F (high). Annual precipitation averages 17.3 Inches. Libby is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 21.4 °F | 33.3 °F | 1.76 in. |
| February | 22.1 °F | 39.5 °F | 1.21 in. |
| March | 26.6 °F | 49.4 °F | 1.77 in. |
| April | 31.6 °F | 59.6 °F | 1.01 in. |
| May | 38.9 °F | 69.8 °F | 1.35 in. |
| June | 45.8 °F | 76.5 °F | 1.65 in. |
| July | 49.4 °F | 87.2 °F | 0.85 in. |
| August | 48.1 °F | 86.9 °F | 0.67 in. |
| September | 41.4 °F | 74.8 °F | 0.93 in. |
| October | 34.2 °F | 56.9 °F | 1.6 in. |
| November | 28.2 °F | 40.3 °F | 2.23 in. |
| December | 22.5 °F | 32.4 °F | 2.28 in. |
| Annual | 34.2 °F | 58.9 °F | 17.31 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| 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 |