Junction, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 46.8 °F (low) to 67 °F (high). Annual precipitation averages 46.9 Inches. Junction 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 | 25.3 °F | 41.4 °F | 3.6 in. |
| February | 27.9 °F | 46.4 °F | 3.25 in. |
| March | 36.0 °F | 56.1 °F | 4.6 in. |
| April | 45.9 °F | 67.8 °F | 4.79 in. |
| May | 56.6 °F | 76.9 °F | 5.08 in. |
| June | 65.0 °F | 85.2 °F | 4.22 in. |
| July | 68.1 °F | 88.1 °F | 4.14 in. |
| August | 65.9 °F | 87.1 °F | 3.01 in. |
| September | 58.5 °F | 82.0 °F | 3.06 in. |
| October | 46.8 °F | 70.3 °F | 3.27 in. |
| November | 36.3 °F | 56.5 °F | 4.01 in. |
| December | 28.7 °F | 45.8 °F | 3.86 in. |
| Annual | 46.8 °F | 67 °F | 46.89 in. |
| 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 : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |