Thompsonville, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 45.6 °F (low) to 66.1 °F (high). Annual precipitation averages 46.8 Inches. Thompsonville 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 | 23.4 °F | 40.4 °F | 3.42 in. |
| February | 26.4 °F | 45.4 °F | 2.97 in. |
| March | 34.9 °F | 55.4 °F | 4.2 in. |
| April | 45.0 °F | 67.1 °F | 5.23 in. |
| May | 55.5 °F | 75.8 °F | 5.19 in. |
| June | 64.0 °F | 84.3 °F | 4.6 in. |
| July | 67.5 °F | 87.4 °F | 3.94 in. |
| August | 65.2 °F | 86.6 °F | 3.03 in. |
| September | 57.0 °F | 80.9 °F | 3.15 in. |
| October | 45.5 °F | 69.6 °F | 3.44 in. |
| November | 35.4 °F | 56.0 °F | 4.16 in. |
| December | 27.5 °F | 44.7 °F | 3.48 in. |
| Annual | 45.6 °F | 66.1 °F | 46.81 in. |
| 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 : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |