Dallas City, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.9 °C (low) to 16.5 °C (high). Annual precipitation averages 1022.6 Millimeters. Dallas City 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. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.6 °C | 0.6 °C | 43.43 mm |
| February | -6.5 °C | 3.1 °C | 50.29 mm |
| March | -0.8 °C | 9.9 °C | 66.55 mm |
| April | 5.4 °C | 17.1 °C | 100.58 mm |
| May | 11.8 °C | 22.8 °C | 134.87 mm |
| June | 17.2 °C | 27.9 °C | 126.49 mm |
| July | 19.3 °C | 29.9 °C | 105.66 mm |
| August | 18.1 °C | 29.1 °C | 98.3 mm |
| September | 13.3 °C | 25.6 °C | 97.79 mm |
| October | 6.8 °C | 18.6 °C | 81.28 mm |
| November | 0.3 °C | 10.3 °C | 66.04 mm |
| December | -5.3 °C | 3.3 °C | 51.31 mm |
| Annual | 5.9 °C | 16.5 °C | 1022.59 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| 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 |