Morrison, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4 °C (low) to 15.2 °C (high). Annual precipitation averages 985 Millimeters. Morrison 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. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.6 °C | -1.3 °C | 42.42 mm |
| February | -8.6 °C | 1.2 °C | 44.96 mm |
| March | -2.6 °C | 8.2 °C | 63.5 mm |
| April | 3.4 °C | 15.7 °C | 96.01 mm |
| May | 9.9 °C | 22.1 °C | 122.94 mm |
| June | 15.4 °C | 27.2 °C | 130.3 mm |
| July | 17.3 °C | 28.8 °C | 105.66 mm |
| August | 16.1 °C | 27.9 °C | 103.63 mm |
| September | 11.4 °C | 24.6 °C | 93.22 mm |
| October | 5 °C | 17.3 °C | 71.12 mm |
| November | -1.3 °C | 8.9 °C | 59.18 mm |
| December | -7.1 °C | 1.7 °C | 52.07 mm |
| Annual | 4 °C | 15.2 °C | 985.01 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |