Prairie du Rocher, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 45.8 °F (low) to 67.2 °F (high). Annual precipitation averages 43.4 Inches. Prairie du Rocher is located in USDA Plant Hardiness Zone 7a. 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 | 23.1 °F | 41.1 °F | 2.5 in. |
| February | 26.6 °F | 46.4 °F | 2.39 in. |
| March | 34.7 °F | 56.3 °F | 3.59 in. |
| April | 44.8 °F | 68.1 °F | 4.88 in. |
| May | 55.7 °F | 77.4 °F | 5.15 in. |
| June | 64.7 °F | 86.3 °F | 4.26 in. |
| July | 68.3 °F | 89.3 °F | 4.16 in. |
| August | 66.1 °F | 88.4 °F | 3.32 in. |
| September | 57.4 °F | 81.8 °F | 3.39 in. |
| October | 45.6 °F | 70.4 °F | 3.19 in. |
| November | 35.5 °F | 56.2 °F | 3.63 in. |
| December | 26.9 °F | 44.9 °F | 2.91 in. |
| Annual | 45.8 °F | 67.2 °F | 43.37 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 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |