Opdyke, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 45.2 °F (low) to 65.1 °F (high). Annual precipitation averages 45.5 Inches. Opdyke 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 | 22.6 °F | 39.1 °F | 3.08 in. |
| February | 25.6 °F | 44.0 °F | 2.75 in. |
| March | 34.2 °F | 54.2 °F | 3.86 in. |
| April | 44.4 °F | 65.8 °F | 4.96 in. |
| May | 55.2 °F | 74.9 °F | 5.13 in. |
| June | 63.9 °F | 83.9 °F | 4.7 in. |
| July | 67.3 °F | 87.0 °F | 4.11 in. |
| August | 64.9 °F | 86.2 °F | 3.27 in. |
| September | 56.7 °F | 80.1 °F | 3.22 in. |
| October | 45.2 °F | 68.5 °F | 3.38 in. |
| November | 35.0 °F | 54.5 °F | 4.0 in. |
| December | 26.9 °F | 43.3 °F | 3.06 in. |
| Annual | 45.2 °F | 65.1 °F | 45.52 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |