Armstrong, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 44.5 °F (low) to 64.2 °F (high). Annual precipitation averages 41.5 Inches. Armstrong 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 | 19.7 °F | 37.0 °F | 1.69 in. |
| February | 23.4 °F | 42.1 °F | 2.07 in. |
| March | 33.3 °F | 53.9 °F | 2.93 in. |
| April | 43.7 °F | 64.9 °F | 4.47 in. |
| May | 54.4 °F | 74.2 °F | 5.22 in. |
| June | 63.5 °F | 82.8 °F | 5.11 in. |
| July | 67.5 °F | 87.1 °F | 4.47 in. |
| August | 65.2 °F | 86.0 °F | 3.8 in. |
| September | 56.6 °F | 79.0 °F | 3.74 in. |
| October | 45.7 °F | 67.4 °F | 3.35 in. |
| November | 34.8 °F | 53.7 °F | 2.68 in. |
| December | 25.8 °F | 41.7 °F | 1.96 in. |
| Annual | 44.5 °F | 64.2 °F | 41.49 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 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |