Helena, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 46.2 °F (low) to 71.2 °F (high). Annual precipitation averages 31.9 Inches. Helena is located in USDA Plant Hardiness Zone 7a. 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 | 23.3 °F | 47.4 °F | 1.0 in. |
| February | 26.2 °F | 51.2 °F | 1.25 in. |
| March | 35.1 °F | 61.3 °F | 2.31 in. |
| April | 43.5 °F | 70.1 °F | 3.03 in. |
| May | 55.0 °F | 79.6 °F | 4.33 in. |
| June | 65.4 °F | 89.9 °F | 4.39 in. |
| July | 69.8 °F | 95.1 °F | 3.24 in. |
| August | 68.3 °F | 93.3 °F | 3.71 in. |
| September | 60.2 °F | 85.5 °F | 2.53 in. |
| October | 47.0 °F | 72.8 °F | 3.08 in. |
| November | 34.7 °F | 59.7 °F | 1.59 in. |
| December | 25.5 °F | 48.3 °F | 1.42 in. |
| Annual | 46.2 °F | 71.2 °F | 31.88 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 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |