Dewey, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 46.8 °F (low) to 70.3 °F (high). Annual precipitation averages 40.1 Inches. Dewey 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 | 23.5 °F | 46.6 °F | 1.48 in. |
| February | 27.0 °F | 51.3 °F | 1.77 in. |
| March | 36.1 °F | 60.7 °F | 2.99 in. |
| April | 45.9 °F | 70.3 °F | 4.19 in. |
| May | 56.5 °F | 78.0 °F | 5.96 in. |
| June | 65.8 °F | 86.7 °F | 5.17 in. |
| July | 70.0 °F | 92.1 °F | 3.71 in. |
| August | 67.9 °F | 91.8 °F | 3.52 in. |
| September | 59.6 °F | 84.2 °F | 3.4 in. |
| October | 47.0 °F | 72.6 °F | 3.58 in. |
| November | 35.5 °F | 60.2 °F | 2.36 in. |
| December | 26.4 °F | 48.9 °F | 1.95 in. |
| Annual | 46.8 °F | 70.3 °F | 40.08 in. |
| 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 : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |