Broadus, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.4 °C (low) to 16 °C (high). Annual precipitation averages 383 Millimeters. Broadus is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -12.1 °C | 1.4 °C | 9.14 mm |
| February | -10.1 °C | 3.5 °C | 13.72 mm |
| March | -5.4 °C | 9.5 °C | 23.11 mm |
| April | -0.1 °C | 15.4 °C | 44.7 mm |
| May | 5.2 °C | 20.4 °C | 70.61 mm |
| June | 10.4 °C | 26.3 °C | 63.25 mm |
| July | 14.1 °C | 31.8 °C | 46.48 mm |
| August | 12.9 °C | 31.4 °C | 30.48 mm |
| September | 7 °C | 25.5 °C | 30.23 mm |
| October | 0.4 °C | 16.7 °C | 28.45 mm |
| November | -6 °C | 8.2 °C | 11.68 mm |
| December | -11.2 °C | 2.2 °C | 11.18 mm |
| Annual | 0.4 °C | 16 °C | 383.03 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |