Alton, Texas has a Hot Semi-Arid Climate climate (Köppen classification: BSh). Average annual temperatures range from 64.2 °F (low) to 86.1 °F (high). Annual precipitation averages 21.6 Inches. Alton is located in USDA Plant Hardiness Zone 10a. The growing season typically runs from the last frost around Frost Rare through the first frost around Jan. 21 - Jan. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 49.0 °F | 71.1 °F | 0.81 in. |
| February | 52.9 °F | 75.8 °F | 0.95 in. |
| March | 58.9 °F | 81.2 °F | 1.2 in. |
| April | 64.8 °F | 87.0 °F | 1.36 in. |
| May | 71.3 °F | 91.8 °F | 2.13 in. |
| June | 75.1 °F | 96.2 °F | 2.51 in. |
| July | 76.2 °F | 97.3 °F | 2.15 in. |
| August | 76.1 °F | 98.5 °F | 1.48 in. |
| September | 72.5 °F | 93.5 °F | 4.57 in. |
| October | 65.6 °F | 88.3 °F | 2.31 in. |
| November | 57.1 °F | 79.5 °F | 1.2 in. |
| December | 50.3 °F | 72.5 °F | 0.95 in. |
| Annual | 64.2 °F | 86.1 °F | 21.62 in. |
| Average First Frost Date | Jan. 21 - Jan. 31 |
| Average Last Frost Date | Frost Rare |
| Average Days With Frost | Frost Free |
| Plant Hardiness Zone | Zone 10a : 30°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 9b : 25°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | BSh - Hot Semi-Arid Climate |