Sulphur, Louisiana has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 14.9 °C (low) to 25.6 °C (high). Annual precipitation averages 1621.5 Millimeters. Sulphur is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Feb. 1 - Feb. 10 through the first frost around Dec. 1 - Dec. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 5.5 °C | 16.3 °C | 156.97 mm |
| February | 7.4 °C | 18.3 °C | 101.85 mm |
| March | 10.8 °C | 21.9 °C | 96.01 mm |
| April | 14.6 °C | 25.3 °C | 116.84 mm |
| May | 19.2 °C | 29.1 °C | 134.11 mm |
| June | 22.6 °C | 31.9 °C | 176.02 mm |
| July | 23.6 °C | 32.9 °C | 163.07 mm |
| August | 23.3 °C | 33.4 °C | 154.94 mm |
| September | 20.8 °C | 31.4 °C | 146.56 mm |
| October | 15.1 °C | 27.2 °C | 123.95 mm |
| November | 9.7 °C | 21.5 °C | 121.16 mm |
| December | 6.6 °C | 17.4 °C | 130.05 mm |
| Annual | 14.9 °C | 25.6 °C | 1621.53 mm |
| Average First Frost Date | Dec. 1 - Dec. 10 |
| Average Last Frost Date | Feb. 1 - Feb. 10 |
| 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 |