Fort Gibson, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 9.9 °C (low) to 22.1 °C (high). Annual precipitation averages 1160.5 Millimeters. Fort Gibson 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 | -2.4 °C | 9.7 °C | 57.91 mm |
| February | -0.4 °C | 12.1 °C | 59.44 mm |
| March | 4.3 °C | 17.1 °C | 95.25 mm |
| April | 9.2 °C | 22.1 °C | 124.21 mm |
| May | 14.8 °C | 26.2 °C | 154.43 mm |
| June | 19.8 °C | 30.8 °C | 125.98 mm |
| July | 22.1 °C | 33.6 °C | 87.88 mm |
| August | 21.2 °C | 33.7 °C | 79.25 mm |
| September | 16.9 °C | 29.4 °C | 109.47 mm |
| October | 10.2 °C | 23.3 °C | 97.28 mm |
| November | 4.1 °C | 16.8 °C | 92.2 mm |
| December | -0.7 °C | 10.8 °C | 77.22 mm |
| Annual | 9.9 °C | 22.1 °C | 1160.52 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |