Washington, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 48.9 °F (low) to 73.1 °F (high). Annual precipitation averages 37.6 Inches. Washington 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 | 26.8 °F | 51.0 °F | 1.44 in. |
| February | 30.6 °F | 55.5 °F | 1.76 in. |
| March | 39.3 °F | 64.5 °F | 2.71 in. |
| April | 47.6 °F | 72.8 °F | 3.79 in. |
| May | 57.9 °F | 80.1 °F | 5.49 in. |
| June | 66.7 °F | 88.5 °F | 4.39 in. |
| July | 70.5 °F | 94.1 °F | 3.34 in. |
| August | 69.2 °F | 94.1 °F | 2.95 in. |
| September | 61.4 °F | 86.1 °F | 4.01 in. |
| October | 49.4 °F | 75.1 °F | 3.51 in. |
| November | 38.3 °F | 62.9 °F | 2.13 in. |
| December | 29.5 °F | 52.5 °F | 2.11 in. |
| Annual | 48.9 °F | 73.1 °F | 37.63 in. |
| 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 7b : 5°F to 10°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |