Quincy, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.7 °F (low) to 63.3 °F (high). Annual precipitation averages 39.2 Inches. Quincy is located in USDA Plant Hardiness Zone 6a. 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 | 18.6 °F | 35.1 °F | 1.78 in. |
| February | 22.4 °F | 40.3 °F | 2.07 in. |
| March | 31.6 °F | 51.8 °F | 2.61 in. |
| April | 42.8 °F | 64.5 °F | 4.03 in. |
| May | 54.0 °F | 74.2 °F | 4.95 in. |
| June | 63.6 °F | 83.2 °F | 4.67 in. |
| July | 67.0 °F | 87.2 °F | 3.9 in. |
| August | 64.9 °F | 85.7 °F | 3.9 in. |
| September | 56.5 °F | 78.9 °F | 3.53 in. |
| October | 45.0 °F | 66.5 °F | 3.18 in. |
| November | 33.6 °F | 52.2 °F | 2.65 in. |
| December | 24.0 °F | 39.8 °F | 1.96 in. |
| Annual | 43.7 °F | 63.3 °F | 39.23 in. |
| 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 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |