Hennepin, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.2 °C (low) to 23.2 °C (high). Annual precipitation averages 940.8 Millimeters. Hennepin is located in USDA Plant Hardiness Zone 8a. 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 | -1.9 °C | 11.3 °C | 40.64 mm |
| February | 0.2 °C | 13.7 °C | 48.26 mm |
| March | 4.9 °C | 18.4 °C | 71.12 mm |
| April | 9.3 °C | 22.9 °C | 90.42 mm |
| May | 14.9 °C | 26.8 °C | 142.49 mm |
| June | 19.9 °C | 31.5 °C | 119.38 mm |
| July | 21.9 °C | 34.5 °C | 69.6 mm |
| August | 21.4 °C | 34.7 °C | 67.31 mm |
| September | 17.2 °C | 30.4 °C | 98.3 mm |
| October | 10.4 °C | 24.4 °C | 86.87 mm |
| November | 4.4 °C | 17.9 °C | 54.1 mm |
| December | -0.7 °C | 12.2 °C | 52.32 mm |
| Annual | 10.2 °C | 23.2 °C | 940.81 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |