Big Timber, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 33.4 °F (low) to 59.8 °F (high). Annual precipitation averages 17 Inches. Big Timber 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. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 17.6 °F | 38.0 °F | 0.57 in. |
| February | 17.6 °F | 40.2 °F | 0.57 in. |
| March | 24.3 °F | 49.1 °F | 0.98 in. |
| April | 31.3 °F | 57.4 °F | 2.22 in. |
| May | 39.5 °F | 66.7 °F | 3.14 in. |
| June | 47.5 °F | 75.9 °F | 2.84 in. |
| July | 53.0 °F | 86.9 °F | 1.45 in. |
| August | 50.9 °F | 85.6 °F | 1.02 in. |
| September | 43.0 °F | 74.8 °F | 1.26 in. |
| October | 33.4 °F | 59.8 °F | 1.49 in. |
| November | 24.7 °F | 46.5 °F | 0.72 in. |
| December | 17.7 °F | 37.2 °F | 0.7 in. |
| Annual | 33.4 °F | 59.8 °F | 16.96 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |