San Leon, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 64.9 °F (low) to 75.3 °F (high). Annual precipitation averages 58 Inches. San Leon is located in USDA Plant Hardiness Zone 10a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 47.9 °F | 60.6 °F | 4.65 in. |
| February | 51.4 °F | 63.4 °F | 3.16 in. |
| March | 57.8 °F | 68.6 °F | 3.37 in. |
| April | 64.3 °F | 74.0 °F | 4.24 in. |
| May | 71.8 °F | 80.3 °F | 4.98 in. |
| June | 77.3 °F | 85.3 °F | 5.88 in. |
| July | 79.0 °F | 87.6 °F | 4.59 in. |
| August | 78.6 °F | 88.3 °F | 6.29 in. |
| September | 75.4 °F | 85.0 °F | 6.42 in. |
| October | 68.0 °F | 78.2 °F | 5.28 in. |
| November | 57.7 °F | 69.7 °F | 4.7 in. |
| December | 49.8 °F | 62.7 °F | 4.44 in. |
| Annual | 64.9 °F | 75.3 °F | 58 in. |
| Average First Frost Date | Frost Rare |
| Average Last Frost Date | |
| Average Days With Frost | Frost Rare |
| 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 | Cfa - Humid Subtropical Climate |