Golconda, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.5 °C (low) to 19.5 °C (high). Annual precipitation averages 1262.6 Millimeters. Golconda is located in USDA Plant Hardiness Zone 7a. 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 | -3.4 °C | 5.7 °C | 99.57 mm |
| February | -2 °C | 8.3 °C | 89.92 mm |
| March | 2.7 °C | 13.7 °C | 121.16 mm |
| April | 7.9 °C | 19.9 °C | 131.57 mm |
| May | 13.7 °C | 24.8 °C | 128.27 mm |
| June | 18.4 °C | 29.4 °C | 112.52 mm |
| July | 20.4 °C | 31 °C | 107.44 mm |
| August | 19.2 °C | 30.4 °C | 76.45 mm |
| September | 15.1 °C | 27.4 °C | 87.88 mm |
| October | 8.6 °C | 21.2 °C | 95.25 mm |
| November | 2.6 °C | 13.9 °C | 104.39 mm |
| December | -1.7 °C | 7.8 °C | 108.2 mm |
| Annual | 8.5 °C | 19.5 °C | 1262.62 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 |