Grain Valley, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.6 °C (low) to 18.3 °C (high). Annual precipitation averages 1096.3 Millimeters. Grain Valley is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.2 °C | 3.4 °C | 35.56 mm |
| February | -4.9 °C | 6.6 °C | 45.47 mm |
| March | 0.3 °C | 12.7 °C | 68.07 mm |
| April | 6.1 °C | 18.6 °C | 107.44 mm |
| May | 12.2 °C | 23.8 °C | 143.26 mm |
| June | 17.6 °C | 28.8 °C | 141.48 mm |
| July | 19.9 °C | 31.2 °C | 128.02 mm |
| August | 18.6 °C | 30.5 °C | 117.09 mm |
| September | 13.7 °C | 26.3 °C | 111.25 mm |
| October | 7 °C | 19.9 °C | 90.17 mm |
| November | 0.7 °C | 12 °C | 61.72 mm |
| December | -4.7 °C | 5.7 °C | 46.74 mm |
| Annual | 6.6 °C | 18.3 °C | 1096.27 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |