Valmeyer, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.3 °C (low) to 19 °C (high). Annual precipitation averages 1112.5 Millimeters. Valmeyer is located in USDA Plant Hardiness Zone 7a. 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 | -4.7 °C | 4.8 °C | 70.1 mm |
| February | -2.7 °C | 7.8 °C | 63.5 mm |
| March | 2.1 °C | 13.3 °C | 95 mm |
| April | 7.8 °C | 19.8 °C | 126.75 mm |
| May | 13.4 °C | 24.4 °C | 127 mm |
| June | 18.1 °C | 29.3 °C | 114.05 mm |
| July | 20.5 °C | 31.1 °C | 101.6 mm |
| August | 19.3 °C | 30.4 °C | 84.07 mm |
| September | 15.3 °C | 26.9 °C | 84.58 mm |
| October | 9.1 °C | 20.5 °C | 79.76 mm |
| November | 2.9 °C | 13.2 °C | 91.44 mm |
| December | -1.9 °C | 7 °C | 74.68 mm |
| Annual | 8.3 °C | 19 °C | 1112.53 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |