Mount Morris, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.9 °F (low) to 58.6 °F (high). Annual precipitation averages 38.5 Inches. Mount Morris is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.3 °F | 28.8 °F | 1.73 in. |
| February | 15.9 °F | 33.2 °F | 1.75 in. |
| March | 26.1 °F | 45.6 °F | 2.36 in. |
| April | 36.3 °F | 59.7 °F | 3.72 in. |
| May | 48.1 °F | 71.2 °F | 4.71 in. |
| June | 58.1 °F | 80.3 °F | 5.1 in. |
| July | 61.3 °F | 83.0 °F | 4.36 in. |
| August | 59.0 °F | 81.6 °F | 3.96 in. |
| September | 50.5 °F | 75.7 °F | 3.61 in. |
| October | 39.5 °F | 62.7 °F | 2.9 in. |
| November | 28.7 °F | 47.2 °F | 2.31 in. |
| December | 18.5 °F | 34.2 °F | 2.03 in. |
| Annual | 37.9 °F | 58.6 °F | 38.54 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |