Armstrong, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 51.2 °F (low) to 74.1 °F (high). Annual precipitation averages 45 Inches. Armstrong is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 30.1 °F | 52.6 °F | 2.45 in. |
| February | 34.2 °F | 57.4 °F | 2.57 in. |
| March | 42.0 °F | 65.0 °F | 3.87 in. |
| April | 49.7 °F | 73.3 °F | 4.09 in. |
| May | 59.9 °F | 80.5 °F | 6.08 in. |
| June | 68.5 °F | 89.0 °F | 4.73 in. |
| July | 72.1 °F | 94.0 °F | 3.29 in. |
| August | 70.5 °F | 94.4 °F | 2.86 in. |
| September | 62.9 °F | 87.2 °F | 3.91 in. |
| October | 51.0 °F | 76.4 °F | 4.25 in. |
| November | 40.9 °F | 64.6 °F | 3.5 in. |
| December | 32.6 °F | 54.8 °F | 3.36 in. |
| Annual | 51.2 °F | 74.1 °F | 44.96 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : 10°F to 15°F |
| Plant Hardiness Zone - 2012 | Zone 7b : 5°F to 10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |