Longview, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.8 °C (low) to 16.9 °C (high). Annual precipitation averages 1007.9 Millimeters. Longview 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 | -7.5 °C | 1.2 °C | 60.45 mm |
| February | -5.8 °C | 3.8 °C | 51.82 mm |
| March | -0.7 °C | 10.3 °C | 71.12 mm |
| April | 5.2 °C | 17.6 °C | 111.51 mm |
| May | 11.6 °C | 23.4 °C | 112.27 mm |
| June | 16.7 °C | 28.1 °C | 115.57 mm |
| July | 18.2 °C | 29.3 °C | 103.38 mm |
| August | 16.9 °C | 28.6 °C | 69.6 mm |
| September | 12.8 °C | 26.1 °C | 80.52 mm |
| October | 6.3 °C | 19 °C | 83.82 mm |
| November | 0.4 °C | 10.8 °C | 84.58 mm |
| December | -4.3 °C | 4 °C | 63.25 mm |
| Annual | 5.8 °C | 16.9 °C | 1007.89 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 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |