Essex, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 29.8 °F (low) to 52.4 °F (high). Annual precipitation averages 44.6 Inches. Essex is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 15.0 °F | 29.5 °F | 5.24 in. |
| February | 15.8 °F | 33.1 °F | 4.08 in. |
| March | 21.6 °F | 41.6 °F | 4.37 in. |
| April | 27.8 °F | 49.7 °F | 3.82 in. |
| May | 35.2 °F | 61.5 °F | 3.33 in. |
| June | 41.8 °F | 68.6 °F | 3.84 in. |
| July | 46.7 °F | 79.9 °F | 1.53 in. |
| August | 45.2 °F | 79.3 °F | 1.16 in. |
| September | 38.3 °F | 67.2 °F | 2.63 in. |
| October | 30.1 °F | 51.4 °F | 3.97 in. |
| November | 23.1 °F | 37.2 °F | 5.45 in. |
| December | 16.7 °F | 29.2 °F | 5.19 in. |
| Annual | 29.8 °F | 52.4 °F | 44.61 in. |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |