Hartshorne, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.1 °C (low) to 22.7 °C (high). Annual precipitation averages 1196.3 Millimeters. Hartshorne is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -1.9 °C | 10.6 °C | 67.06 mm |
| February | 0.2 °C | 12.8 °C | 65.53 mm |
| March | 4.8 °C | 17.8 °C | 98.04 mm |
| April | 9.4 °C | 22.4 °C | 122.17 mm |
| May | 15 °C | 26.3 °C | 153.67 mm |
| June | 19.8 °C | 30.9 °C | 117.6 mm |
| July | 21.8 °C | 33.9 °C | 91.95 mm |
| August | 21 °C | 34 °C | 80.52 mm |
| September | 16.8 °C | 30.1 °C | 108.71 mm |
| October | 10.3 °C | 23.9 °C | 107.95 mm |
| November | 4.6 °C | 17.4 °C | 94.49 mm |
| December | -0.2 °C | 11.8 °C | 88.65 mm |
| Annual | 10.1 °C | 22.7 °C | 1196.34 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |