New Boston, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.4 °C (low) to 16.1 °C (high). Annual precipitation averages 922.5 Millimeters. New Boston is located in USDA Plant Hardiness Zone 5b. 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 | -9.1 °C | -0.2 °C | 35.81 mm |
| February | -7.3 °C | 2.2 °C | 42.42 mm |
| March | -1.2 °C | 9.2 °C | 61.47 mm |
| April | 4.9 °C | 16.7 °C | 88.9 mm |
| May | 11.4 °C | 22.7 °C | 121.92 mm |
| June | 16.9 °C | 28 °C | 121.92 mm |
| July | 18.8 °C | 29.9 °C | 92.46 mm |
| August | 17.4 °C | 28.8 °C | 99.31 mm |
| September | 12.9 °C | 25.2 °C | 86.87 mm |
| October | 6.4 °C | 18.1 °C | 69.09 mm |
| November | 0 °C | 9.9 °C | 55.88 mm |
| December | -5.8 °C | 2.6 °C | 46.48 mm |
| Annual | 5.4 °C | 16.1 °C | 922.53 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 5b : -26.1°C to -23.3°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 |