Arlington, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.4 °F (low) to 59.6 °F (high). Annual precipitation averages 37.6 Inches. Arlington 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 13.8 °F | 30.2 °F | 1.77 in. |
| February | 17.5 °F | 34.7 °F | 1.75 in. |
| March | 27.2 °F | 47.2 °F | 2.38 in. |
| April | 37.9 °F | 60.6 °F | 3.58 in. |
| May | 49.7 °F | 71.9 °F | 4.67 in. |
| June | 59.6 °F | 80.7 °F | 4.72 in. |
| July | 63.1 °F | 83.6 °F | 4.03 in. |
| August | 60.7 °F | 81.8 °F | 3.88 in. |
| September | 52.6 °F | 76.3 °F | 3.48 in. |
| October | 41.0 °F | 63.7 °F | 2.97 in. |
| November | 29.9 °F | 48.4 °F | 2.44 in. |
| December | 19.8 °F | 35.5 °F | 1.97 in. |
| Annual | 39.4 °F | 59.6 °F | 37.64 in. |
| 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 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |