Blackwell, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.4 °C (low) to 21.8 °C (high). Annual precipitation averages 935.5 Millimeters. Blackwell 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 Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.4 °C | 8.3 °C | 28.45 mm |
| February | -2.7 °C | 10.8 °C | 35.81 mm |
| March | 2.3 °C | 16.3 °C | 67.56 mm |
| April | 7.2 °C | 21.7 °C | 96.52 mm |
| May | 13.6 °C | 26.4 °C | 123.95 mm |
| June | 19 °C | 31.7 °C | 126.24 mm |
| July | 21.4 °C | 34.4 °C | 109.73 mm |
| August | 20.4 °C | 33.9 °C | 93.47 mm |
| September | 15.9 °C | 29.8 °C | 75.95 mm |
| October | 8.8 °C | 23.1 °C | 91.19 mm |
| November | 2.2 °C | 15.8 °C | 47.5 mm |
| December | -3 °C | 9.2 °C | 39.12 mm |
| Annual | 8.4 °C | 21.8 °C | 935.49 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |