Twin Bridges, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -1.5 °C (low) to 14.8 °C (high). Annual precipitation averages 240.5 Millimeters. Twin Bridges is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Jun. 1 - Jun. 10 through the first frost around Aug. 21 - Aug. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.3 °C | 2.1 °C | 6.1 mm |
| February | -9.2 °C | 4.1 °C | 5.59 mm |
| March | -5.4 °C | 9.2 °C | 9.14 mm |
| April | -1.9 °C | 13.8 °C | 22.61 mm |
| May | 2.5 °C | 19 °C | 42.67 mm |
| June | 6.2 °C | 23.6 °C | 54.86 mm |
| July | 8.4 °C | 29.3 °C | 23.37 mm |
| August | 7.2 °C | 28.8 °C | 19.05 mm |
| September | 3.3 °C | 23.3 °C | 22.1 mm |
| October | -1.6 °C | 15.6 °C | 19.81 mm |
| November | -6.4 °C | 7.1 °C | 7.87 mm |
| December | -10.7 °C | 1.4 °C | 7.37 mm |
| Annual | -1.5 °C | 14.8 °C | 240.54 mm |
| Average First Frost Date | Aug. 21 - Aug. 31 |
| Average Last Frost Date | Jun. 1 - Jun. 10 |
| Average Days With Frost | Over 180 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 | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |