Hennessey, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 47.4 °F (low) to 71.6 °F (high). Annual precipitation averages 33.7 Inches. Hennessey is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 24.8 °F | 48.1 °F | 1.08 in. |
| February | 27.8 °F | 52.0 °F | 1.48 in. |
| March | 36.4 °F | 61.6 °F | 2.46 in. |
| April | 44.9 °F | 70.5 °F | 3.62 in. |
| May | 56.1 °F | 79.5 °F | 4.85 in. |
| June | 66.1 °F | 89.5 °F | 4.63 in. |
| July | 70.5 °F | 95.1 °F | 3.04 in. |
| August | 69.0 °F | 93.7 °F | 3.48 in. |
| September | 61.1 °F | 86.0 °F | 2.62 in. |
| October | 48.4 °F | 73.4 °F | 3.08 in. |
| November | 36.3 °F | 60.4 °F | 1.8 in. |
| December | 27.1 °F | 49.3 °F | 1.59 in. |
| Annual | 47.4 °F | 71.6 °F | 33.73 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |