Fort Supply, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 6.9 °C (low) to 22 °C (high). Annual precipitation averages 617 Millimeters. Fort Supply is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.7 °C | 9.4 °C | 20.32 mm |
| February | -4.1 °C | 11.3 °C | 23.88 mm |
| March | 0.9 °C | 16.8 °C | 45.47 mm |
| April | 5.8 °C | 21.8 °C | 51.56 mm |
| May | 12 °C | 26.7 °C | 80.26 mm |
| June | 17.8 °C | 31.6 °C | 91.69 mm |
| July | 20.3 °C | 34.6 °C | 67.06 mm |
| August | 19.2 °C | 33.9 °C | 73.66 mm |
| September | 14.4 °C | 29.6 °C | 47.75 mm |
| October | 7.1 °C | 22.9 °C | 60.2 mm |
| November | 0.2 °C | 15.8 °C | 27.94 mm |
| December | -4.8 °C | 9.7 °C | 27.18 mm |
| Annual | 6.9 °C | 22 °C | 616.97 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |