Germantown, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.7 °C (low) to 18.8 °C (high). Annual precipitation averages 1063.3 Millimeters. Germantown 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.4 °C | 4.1 °C | 68.58 mm |
| February | -3.6 °C | 6.9 °C | 57.91 mm |
| March | 1.6 °C | 12.8 °C | 82.04 mm |
| April | 7.4 °C | 19.4 °C | 117.86 mm |
| May | 13.4 °C | 24.5 °C | 121.67 mm |
| June | 18.3 °C | 29.4 °C | 119.38 mm |
| July | 20.2 °C | 31.3 °C | 97.79 mm |
| August | 18.9 °C | 30.8 °C | 78.49 mm |
| September | 14.2 °C | 26.9 °C | 81.28 mm |
| October | 7.8 °C | 20.5 °C | 77.22 mm |
| November | 1.9 °C | 12.8 °C | 91.95 mm |
| December | -2.9 °C | 6.6 °C | 69.09 mm |
| Annual | 7.7 °C | 18.8 °C | 1063.26 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |