Brockton, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 29.1 °F (low) to 55.9 °F (high). Annual precipitation averages 14.3 Inches. Brockton is located in USDA Plant Hardiness Zone 4a. 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 | 1.8 °F | 23.4 °F | 0.32 in. |
| February | 5.6 °F | 28.8 °F | 0.28 in. |
| March | 17.5 °F | 41.8 °F | 0.51 in. |
| April | 29.1 °F | 57.4 °F | 1.03 in. |
| May | 40.0 °F | 68.8 °F | 2.22 in. |
| June | 50.5 °F | 77.7 °F | 2.96 in. |
| July | 55.3 °F | 85.7 °F | 2.56 in. |
| August | 53.1 °F | 85.7 °F | 1.47 in. |
| September | 42.9 °F | 74.9 °F | 1.23 in. |
| October | 30.4 °F | 58.1 °F | 0.86 in. |
| November | 17.3 °F | 40.5 °F | 0.45 in. |
| December | 6.2 °F | 27.7 °F | 0.37 in. |
| Annual | 29.1 °F | 55.9 °F | 14.26 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4a : -30°F to -25°F |
| Plant Hardiness Zone - 2012 | Zone 3b : -35°F to -30°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |