Ohlman, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.9 °F (low) to 63.9 °F (high). Annual precipitation averages 40.7 Inches. Ohlman is located in USDA Plant Hardiness Zone 6b. 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 | 20.2 °F | 35.8 °F | 2.48 in. |
| February | 23.6 °F | 41.0 °F | 2.12 in. |
| March | 32.6 °F | 52.2 °F | 2.93 in. |
| April | 42.9 °F | 65.1 °F | 4.39 in. |
| May | 54.1 °F | 75.1 °F | 4.73 in. |
| June | 62.9 °F | 83.6 °F | 4.69 in. |
| July | 66.0 °F | 86.7 °F | 3.82 in. |
| August | 63.7 °F | 85.5 °F | 3.19 in. |
| September | 56.0 °F | 80.3 °F | 3.16 in. |
| October | 44.9 °F | 67.9 °F | 3.31 in. |
| November | 34.2 °F | 52.7 °F | 3.33 in. |
| December | 25.5 °F | 40.8 °F | 2.5 in. |
| Annual | 43.9 °F | 63.9 °F | 40.65 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |