Ronan, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 34.2 °F (low) to 56.9 °F (high). Annual precipitation averages 17 Inches. Ronan is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 20.6 °F | 34.3 °F | 1.29 in. |
| February | 20.9 °F | 37.9 °F | 1.05 in. |
| March | 26.4 °F | 47.6 °F | 1.13 in. |
| April | 32.5 °F | 55.6 °F | 1.67 in. |
| May | 39.5 °F | 65.2 °F | 2.06 in. |
| June | 46.0 °F | 71.9 °F | 2.73 in. |
| July | 51.1 °F | 83.3 °F | 0.93 in. |
| August | 49.9 °F | 83.0 °F | 0.84 in. |
| September | 42.8 °F | 71.8 °F | 1.3 in. |
| October | 33.9 °F | 56.2 °F | 1.49 in. |
| November | 26.3 °F | 41.8 °F | 1.3 in. |
| December | 20.8 °F | 33.7 °F | 1.23 in. |
| Annual | 34.2 °F | 56.9 °F | 17.02 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |