Big Timber, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.8 °C (low) to 15.5 °C (high). Annual precipitation averages 430.8 Millimeters. 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 | -8 °C | 3.3 °C | 14.48 mm |
| February | -8 °C | 4.6 °C | 14.48 mm |
| March | -4.3 °C | 9.5 °C | 24.89 mm |
| April | -0.4 °C | 14.1 °C | 56.39 mm |
| May | 4.2 °C | 19.3 °C | 79.76 mm |
| June | 8.6 °C | 24.4 °C | 72.14 mm |
| July | 11.7 °C | 30.5 °C | 36.83 mm |
| August | 10.5 °C | 29.8 °C | 25.91 mm |
| September | 6.1 °C | 23.8 °C | 32 mm |
| October | 0.8 °C | 15.4 °C | 37.85 mm |
| November | -4.1 °C | 8.1 °C | 18.29 mm |
| December | -7.9 °C | 2.9 °C | 17.78 mm |
| Annual | 0.8 °C | 15.5 °C | 430.8 mm |
| 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 : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |