Lewistown Heights, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 31.5 °F (low) to 55.9 °F (high). Annual precipitation averages 16.1 Inches. Lewistown Heights 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 | 13.9 °F | 34.5 °F | 0.59 in. |
| February | 14.3 °F | 35.5 °F | 0.58 in. |
| March | 21.6 °F | 44.3 °F | 0.77 in. |
| April | 29.8 °F | 53.0 °F | 1.69 in. |
| May | 38.3 °F | 62.2 °F | 2.33 in. |
| June | 46.5 °F | 72.4 °F | 3.31 in. |
| July | 52.0 °F | 81.1 °F | 1.72 in. |
| August | 50.7 °F | 81.1 °F | 1.48 in. |
| September | 42.2 °F | 70.6 °F | 1.29 in. |
| October | 31.8 °F | 56.5 °F | 1.14 in. |
| November | 22.0 °F | 43.9 °F | 0.66 in. |
| December | 14.6 °F | 35.2 °F | 0.54 in. |
| Annual | 31.5 °F | 55.9 °F | 16.1 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 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |