Itasca, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.9 °C (low) to 15 °C (high). Annual precipitation averages 984.5 Millimeters. Itasca is located in USDA Plant Hardiness Zone 6a. 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 | -8.9 °C | -0.5 °C | 53.34 mm |
| February | -7.4 °C | 1.7 °C | 51.31 mm |
| March | -2.1 °C | 7.8 °C | 58.17 mm |
| April | 3.5 °C | 14.7 °C | 96.52 mm |
| May | 9.6 °C | 21 °C | 121.16 mm |
| June | 15.2 °C | 26.6 °C | 114.55 mm |
| July | 18.1 °C | 28.9 °C | 93.22 mm |
| August | 17.3 °C | 27.8 °C | 104.14 mm |
| September | 12.7 °C | 24.1 °C | 85.34 mm |
| October | 6 °C | 16.9 °C | 84.84 mm |
| November | -0.2 °C | 8.9 °C | 65.28 mm |
| December | -5.6 °C | 2.4 °C | 56.64 mm |
| Annual | 4.9 °C | 15 °C | 984.51 mm |
| 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 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 |