Mount Calm, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 55.4 °F (low) to 77.4 °F (high). Annual precipitation averages 38.8 Inches. Mount Calm is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 36.0 °F | 57.9 °F | 2.83 in. |
| February | 39.8 °F | 62.0 °F | 2.81 in. |
| March | 46.8 °F | 68.8 °F | 3.62 in. |
| April | 54.1 °F | 76.4 °F | 3.42 in. |
| May | 63.2 °F | 83.7 °F | 4.57 in. |
| June | 70.6 °F | 91.3 °F | 3.73 in. |
| July | 73.5 °F | 95.3 °F | 1.74 in. |
| August | 73.4 °F | 96.1 °F | 2.41 in. |
| September | 66.8 °F | 89.9 °F | 3.07 in. |
| October | 56.1 °F | 79.7 °F | 4.43 in. |
| November | 46.1 °F | 68.0 °F | 3.03 in. |
| December | 38.0 °F | 59.6 °F | 3.14 in. |
| Annual | 55.4 °F | 77.4 °F | 38.8 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8a : 10°F to 15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |