Stockton, Illinois has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 37.8 °F (low) to 57.1 °F (high). Annual precipitation averages 37.9 Inches. Stockton is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 11.6 °F | 27.4 °F | 1.33 in. |
| February | 15.0 °F | 31.7 °F | 1.57 in. |
| March | 25.6 °F | 44.2 °F | 2.11 in. |
| April | 36.4 °F | 58.0 °F | 3.84 in. |
| May | 48.2 °F | 69.6 °F | 4.27 in. |
| June | 58.3 °F | 78.7 °F | 5.66 in. |
| July | 61.4 °F | 81.6 °F | 4.57 in. |
| August | 59.3 °F | 79.9 °F | 4.02 in. |
| September | 51.1 °F | 73.9 °F | 3.57 in. |
| October | 39.8 °F | 61.2 °F | 2.89 in. |
| November | 28.7 °F | 45.7 °F | 2.35 in. |
| December | 17.9 °F | 32.8 °F | 1.75 in. |
| Annual | 37.8 °F | 57.1 °F | 37.93 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |