Simpson, Louisiana has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 56 °F (low) to 77.5 °F (high). Annual precipitation averages 58.1 Inches. Simpson is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Mar. 1 - Mar. 10 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 38.6 °F | 59.3 °F | 5.95 in. |
| February | 41.7 °F | 63.5 °F | 4.91 in. |
| March | 48.4 °F | 70.9 °F | 4.87 in. |
| April | 55.2 °F | 77.7 °F | 5.39 in. |
| May | 63.8 °F | 84.6 °F | 4.71 in. |
| June | 70.3 °F | 90.2 °F | 4.75 in. |
| July | 72.7 °F | 92.4 °F | 4.09 in. |
| August | 72.2 °F | 93.2 °F | 3.79 in. |
| September | 67.0 °F | 88.8 °F | 4.27 in. |
| October | 55.9 °F | 79.8 °F | 4.26 in. |
| November | 46.0 °F | 68.9 °F | 5.4 in. |
| December | 40.5 °F | 61.2 °F | 5.66 in. |
| Annual | 56 °F | 77.5 °F | 58.05 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 1 - Mar. 10 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9a : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |