Cosby, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.7 °C (low) to 17.5 °C (high). Annual precipitation averages 929.7 Millimeters. Cosby 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 | -8.6 °C | 2.1 °C | 22.1 mm |
| February | -6.4 °C | 4.9 °C | 28.7 mm |
| March | -0.6 °C | 11.8 °C | 60.2 mm |
| April | 5.1 °C | 17.8 °C | 93.98 mm |
| May | 11.6 °C | 23.3 °C | 127.76 mm |
| June | 16.9 °C | 28.5 °C | 130.81 mm |
| July | 19.2 °C | 30.6 °C | 117.35 mm |
| August | 18 °C | 29.9 °C | 93.22 mm |
| September | 13.1 °C | 26 °C | 92.46 mm |
| October | 6.3 °C | 19.1 °C | 77.72 mm |
| November | -0.2 °C | 11.6 °C | 46.23 mm |
| December | -5.8 °C | 4.4 °C | 39.12 mm |
| Annual | 5.7 °C | 17.5 °C | 929.65 mm |
| 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 : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |