Fortescue, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.5 °F (low) to 63.8 °F (high). Annual precipitation averages 35.9 Inches. Fortescue is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 15.9 °F | 35.4 °F | 0.8 in. |
| February | 19.4 °F | 40.6 °F | 1.19 in. |
| March | 30.2 °F | 53.6 °F | 2.12 in. |
| April | 40.6 °F | 64.8 °F | 3.6 in. |
| May | 52.6 °F | 74.9 °F | 5.08 in. |
| June | 62.8 °F | 83.6 °F | 4.83 in. |
| July | 66.2 °F | 87.3 °F | 4.97 in. |
| August | 63.3 °F | 85.8 °F | 3.9 in. |
| September | 54.9 °F | 79.6 °F | 3.27 in. |
| October | 42.3 °F | 67.4 °F | 2.93 in. |
| November | 30.1 °F | 52.9 °F | 1.89 in. |
| December | 19.4 °F | 39.4 °F | 1.33 in. |
| Annual | 41.5 °F | 63.8 °F | 35.91 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |