Naperville, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.1 °F (low) to 59.9 °F (high). Annual precipitation averages 39.6 Inches. Naperville 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 | 15.5 °F | 31.4 °F | 2.07 in. |
| February | 18.1 °F | 35.3 °F | 2.02 in. |
| March | 27.7 °F | 47.2 °F | 2.39 in. |
| April | 38.1 °F | 60.1 °F | 3.95 in. |
| May | 49.1 °F | 71.3 °F | 4.9 in. |
| June | 59.2 °F | 81.0 °F | 4.58 in. |
| July | 63.6 °F | 84.8 °F | 3.94 in. |
| August | 62.0 °F | 82.9 °F | 4.1 in. |
| September | 54.1 °F | 76.6 °F | 3.28 in. |
| October | 42.0 °F | 63.5 °F | 3.59 in. |
| November | 30.9 °F | 48.7 °F | 2.58 in. |
| December | 21.3 °F | 36.5 °F | 2.23 in. |
| Annual | 40.1 °F | 59.9 °F | 39.63 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 |