Naples, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.1 °C (low) to 17.8 °C (high). Annual precipitation averages 1006.1 Millimeters. Naples is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.2 °C | 2.2 °C | 54.36 mm |
| February | -5.3 °C | 5.1 °C | 48.51 mm |
| March | -0.3 °C | 11.4 °C | 69.34 mm |
| April | 5.6 °C | 18.4 °C | 101.85 mm |
| May | 11.7 °C | 23.8 °C | 118.36 mm |
| June | 16.8 °C | 28.7 °C | 122.43 mm |
| July | 18.9 °C | 30.6 °C | 105.41 mm |
| August | 17.4 °C | 29.9 °C | 88.14 mm |
| September | 12.9 °C | 26.6 °C | 87.88 mm |
| October | 6.5 °C | 19.8 °C | 77.47 mm |
| November | 0.5 °C | 11.8 °C | 74.17 mm |
| December | -4.3 °C | 4.9 °C | 58.17 mm |
| Annual | 6.1 °C | 17.8 °C | 1006.09 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| 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 |