Twin Bridges, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 29.3 °F (low) to 58.6 °F (high). Annual precipitation averages 9.5 Inches. 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 | 13.4 °F | 35.7 °F | 0.24 in. |
| February | 15.5 °F | 39.3 °F | 0.22 in. |
| March | 22.3 °F | 48.5 °F | 0.36 in. |
| April | 28.6 °F | 56.9 °F | 0.89 in. |
| May | 36.5 °F | 66.2 °F | 1.68 in. |
| June | 43.2 °F | 74.5 °F | 2.16 in. |
| July | 47.1 °F | 84.7 °F | 0.92 in. |
| August | 44.9 °F | 83.8 °F | 0.75 in. |
| September | 37.9 °F | 74.0 °F | 0.87 in. |
| October | 29.1 °F | 60.1 °F | 0.78 in. |
| November | 20.4 °F | 44.7 °F | 0.31 in. |
| December | 12.8 °F | 34.6 °F | 0.29 in. |
| Annual | 29.3 °F | 58.6 °F | 9.47 in. |
| 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 : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |