Alto, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 55.2 °F (low) to 77.5 °F (high). Annual precipitation averages 48.3 Inches. Alto is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 1 - Mar. 10 through the first frost around Nov. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 37.1 °F | 58.9 °F | 4.4 in. |
| February | 40.6 °F | 63.0 °F | 3.85 in. |
| March | 47.2 °F | 69.9 °F | 4.33 in. |
| April | 53.9 °F | 77.2 °F | 3.71 in. |
| May | 63.2 °F | 84.3 °F | 4.36 in. |
| June | 70.1 °F | 90.5 °F | 4.42 in. |
| July | 72.4 °F | 94.0 °F | 2.67 in. |
| August | 71.9 °F | 94.9 °F | 3.48 in. |
| September | 66.0 °F | 88.9 °F | 3.56 in. |
| October | 55.5 °F | 79.4 °F | 4.56 in. |
| November | 45.7 °F | 68.5 °F | 4.35 in. |
| December | 38.9 °F | 60.5 °F | 4.58 in. |
| Annual | 55.2 °F | 77.5 °F | 48.27 in. |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Mar. 1 - Mar. 10 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |