Galena, Missouri has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 6.8 °C (low) to 20.3 °C (high). Annual precipitation averages 1168.2 Millimeters. Galena is located in USDA Plant Hardiness Zone 6b. 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 | -5.2 °C | 7.1 °C | 68.58 mm |
| February | -3.5 °C | 9.8 °C | 67.06 mm |
| March | 1 °C | 15.1 °C | 105.92 mm |
| April | 6.1 °C | 20.6 °C | 121.16 mm |
| May | 11.8 °C | 24.8 °C | 130.56 mm |
| June | 16.7 °C | 29.6 °C | 116.84 mm |
| July | 18.9 °C | 32.3 °C | 107.19 mm |
| August | 18.1 °C | 31.9 °C | 78.23 mm |
| September | 13.3 °C | 27.6 °C | 118.11 mm |
| October | 6.7 °C | 21.7 °C | 77.22 mm |
| November | 1 °C | 14.6 °C | 104.39 mm |
| December | -3.4 °C | 8.9 °C | 72.9 mm |
| Annual | 6.8 °C | 20.3 °C | 1168.16 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 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 | Cfa - Humid Subtropical Climate |