Morton, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.1 °C (low) to 16.5 °C (high). Annual precipitation averages 983.2 Millimeters. Morton is located in USDA Plant Hardiness Zone 6a. 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 | -8.8 °C | 0.4 °C | 56.39 mm |
| February | -6.9 °C | 3.2 °C | 51.56 mm |
| March | -1.6 °C | 9.9 °C | 65.79 mm |
| April | 4.4 °C | 17.1 °C | 98.55 mm |
| May | 10.8 °C | 23 °C | 120.9 mm |
| June | 16.2 °C | 27.9 °C | 108.71 mm |
| July | 18 °C | 29.7 °C | 102.62 mm |
| August | 16.8 °C | 28.8 °C | 85.6 mm |
| September | 12.4 °C | 25.9 °C | 84.07 mm |
| October | 5.9 °C | 18.7 °C | 81.28 mm |
| November | -0.4 °C | 10.4 °C | 73.41 mm |
| December | -5.7 °C | 3.3 °C | 54.36 mm |
| Annual | 5.1 °C | 16.5 °C | 983.24 mm |
| 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 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |