Forgan, Oklahoma has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 42 °F (low) to 71.1 °F (high). Annual precipitation averages 20.9 Inches. Forgan is located in USDA Plant Hardiness Zone 6b. 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 | 19.6 °F | 48.3 °F | 0.54 in. |
| February | 22.0 °F | 51.7 °F | 0.58 in. |
| March | 30.8 °F | 61.4 °F | 1.42 in. |
| April | 39.5 °F | 70.4 °F | 1.86 in. |
| May | 50.6 °F | 79.9 °F | 2.53 in. |
| June | 61.4 °F | 89.3 °F | 3.35 in. |
| July | 66.3 °F | 94.2 °F | 2.65 in. |
| August | 64.5 °F | 92.2 °F | 2.87 in. |
| September | 56.1 °F | 85.1 °F | 1.42 in. |
| October | 42.5 °F | 72.4 °F | 1.93 in. |
| November | 29.6 °F | 59.6 °F | 0.8 in. |
| December | 21.0 °F | 48.3 °F | 0.91 in. |
| Annual | 42 °F | 71.1 °F | 20.86 in. |
| 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 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |