Harvey, Louisiana has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 61.3 °F (low) to 78.4 °F (high). Annual precipitation averages 66 Inches. Harvey is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 44.6 °F | 62.3 °F | 5.53 in. |
| February | 48.0 °F | 66.0 °F | 4.22 in. |
| March | 54.0 °F | 72.1 °F | 4.64 in. |
| April | 60.5 °F | 78.4 °F | 4.98 in. |
| May | 68.1 °F | 85.3 °F | 5.41 in. |
| June | 73.8 °F | 90.0 °F | 7.25 in. |
| July | 75.7 °F | 91.5 °F | 7.59 in. |
| August | 75.7 °F | 91.3 °F | 7.49 in. |
| September | 72.4 °F | 87.9 °F | 5.86 in. |
| October | 63.0 °F | 80.5 °F | 3.91 in. |
| November | 52.7 °F | 71.0 °F | 4.02 in. |
| December | 47.0 °F | 64.6 °F | 5.14 in. |
| Annual | 61.3 °F | 78.4 °F | 66.04 in. |
| Average First Frost Date | Frost Rare |
| Average Last Frost Date | |
| Average Days With Frost | Frost Rare |
| Plant Hardiness Zone | Zone 9b : 25°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 9b : 25°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |