Westlake, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 12.9 °C (low) to 24.8 °C (high). Annual precipitation averages 964.7 Millimeters. Westlake 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 | 1.4 °C | 13.6 °C | 62.23 mm |
| February | 3.4 °C | 15.7 °C | 67.82 mm |
| March | 7.8 °C | 19.9 °C | 84.58 mm |
| April | 12.1 °C | 24.4 °C | 85.6 mm |
| May | 17.4 °C | 28.5 °C | 114.81 mm |
| June | 21.9 °C | 33.1 °C | 97.03 mm |
| July | 23.9 °C | 35.5 °C | 57.66 mm |
| August | 23.7 °C | 35.8 °C | 60.2 mm |
| September | 19.6 °C | 31.7 °C | 77.98 mm |
| October | 13.2 °C | 26 °C | 107.95 mm |
| November | 7.4 °C | 19.4 °C | 72.14 mm |
| December | 2.5 °C | 14.4 °C | 76.71 mm |
| Annual | 12.9 °C | 24.8 °C | 964.71 mm |
| 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 : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |