Gillis, Louisiana has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 14.6 °C (low) to 25.6 °C (high). Annual precipitation averages 1627.6 Millimeters. Gillis 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 | 5.2 °C | 16.2 °C | 162.05 mm |
| February | 7.2 °C | 18.3 °C | 107.7 mm |
| March | 10.6 °C | 21.9 °C | 99.06 mm |
| April | 14.3 °C | 25.4 °C | 124.71 mm |
| May | 18.8 °C | 29.2 °C | 141.22 mm |
| June | 22.2 °C | 32 °C | 169.67 mm |
| July | 23.3 °C | 33.1 °C | 148.84 mm |
| August | 23.1 °C | 33.4 °C | 150.62 mm |
| September | 20.5 °C | 31.4 °C | 139.45 mm |
| October | 14.7 °C | 27.2 °C | 127.51 mm |
| November | 9.3 °C | 21.4 °C | 123.7 mm |
| December | 6.2 °C | 17.3 °C | 133.1 mm |
| Annual | 14.6 °C | 25.6 °C | 1627.63 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 |