Westlake, Louisiana has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 15 °C (low) to 25.5 °C (high). Annual precipitation averages 1629.9 Millimeters. Westlake is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Feb. 11 - Feb. 20 through the first frost around Dec. 1 - Dec. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 5.6 °C | 16.2 °C | 160.27 mm |
| February | 7.5 °C | 18.3 °C | 104.39 mm |
| March | 10.9 °C | 21.8 °C | 96.77 mm |
| April | 14.7 °C | 25.3 °C | 118.87 mm |
| May | 19.2 °C | 29 °C | 138.43 mm |
| June | 22.6 °C | 31.9 °C | 175.77 mm |
| July | 23.7 °C | 32.8 °C | 164.08 mm |
| August | 23.4 °C | 33.3 °C | 157.48 mm |
| September | 20.9 °C | 31.3 °C | 141.73 mm |
| October | 15.2 °C | 27.1 °C | 123.19 mm |
| November | 9.7 °C | 21.5 °C | 119.13 mm |
| December | 6.6 °C | 17.4 °C | 129.79 mm |
| Annual | 15 °C | 25.5 °C | 1629.9 mm |
| Average First Frost Date | Dec. 1 - Dec. 10 |
| Average Last Frost Date | Feb. 11 - Feb. 20 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |