Cornish, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.6 °C (low) to 23.8 °C (high). Annual precipitation averages 867.4 Millimeters. Cornish is located in USDA Plant Hardiness Zone 8a. 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 | -1.2 °C | 12.1 °C | 41.15 mm |
| February | 0.8 °C | 14.2 °C | 50.04 mm |
| March | 5.4 °C | 18.9 °C | 68.58 mm |
| April | 9.7 °C | 23.3 °C | 81.28 mm |
| May | 15.2 °C | 27.4 °C | 123.44 mm |
| June | 20.2 °C | 32.1 °C | 96.52 mm |
| July | 22.2 °C | 35.1 °C | 61.21 mm |
| August | 21.7 °C | 35.3 °C | 65.79 mm |
| September | 17.5 °C | 31.1 °C | 91.95 mm |
| October | 10.8 °C | 24.9 °C | 85.09 mm |
| November | 4.8 °C | 18.4 °C | 53.09 mm |
| December | -0.2 °C | 12.8 °C | 49.28 mm |
| Annual | 10.6 °C | 23.8 °C | 867.42 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 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 |