Basin, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 26.3 °F (low) to 53.8 °F (high). Annual precipitation averages 15.2 Inches. Basin is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Aug. 21 - Aug. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 10.0 °F | 33.2 °F | 0.89 in. |
| February | 12.1 °F | 35.9 °F | 0.72 in. |
| March | 19.1 °F | 43.7 °F | 0.99 in. |
| April | 25.3 °F | 50.7 °F | 1.27 in. |
| May | 32.8 °F | 60.0 °F | 1.85 in. |
| June | 39.4 °F | 68.4 °F | 2.67 in. |
| July | 44.8 °F | 79.7 °F | 1.63 in. |
| August | 43.0 °F | 79.0 °F | 1.42 in. |
| September | 35.9 °F | 68.3 °F | 1.07 in. |
| October | 26.7 °F | 54.1 °F | 0.9 in. |
| November | 16.9 °F | 40.7 °F | 0.83 in. |
| December | 9.3 °F | 31.9 °F | 0.93 in. |
| Annual | 26.3 °F | 53.8 °F | 15.17 in. |
| Average First Frost Date | Aug. 21 - Aug. 31 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |