Chester, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 29.4 °F (low) to 56.4 °F (high). Annual precipitation averages 11.5 Inches. Chester is located in USDA Plant Hardiness Zone 3b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep.1 - Sep. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.1 °F | 30.8 °F | 0.47 in. |
| February | 10.1 °F | 34.9 °F | 0.36 in. |
| March | 18.8 °F | 44.1 °F | 0.45 in. |
| April | 29.0 °F | 56.1 °F | 0.97 in. |
| May | 38.7 °F | 65.8 °F | 1.69 in. |
| June | 46.8 °F | 73.6 °F | 2.62 in. |
| July | 52.1 °F | 83.5 °F | 1.3 in. |
| August | 50.4 °F | 83.0 °F | 1.08 in. |
| September | 41.5 °F | 72.1 °F | 0.9 in. |
| October | 29.9 °F | 57.7 °F | 0.66 in. |
| November | 18.7 °F | 42.7 °F | 0.52 in. |
| December | 9.7 °F | 32.8 °F | 0.45 in. |
| Annual | 29.4 °F | 56.4 °F | 11.47 in. |
| Average First Frost Date | Sep.1 - Sep. 10 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 3b : -35°F to -30°F |
| Plant Hardiness Zone - 2012 | Zone 3b : -35°F to -30°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |