Basco, 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 17 °C (high). Annual precipitation averages 1017.8 Millimeters. Basco 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 | -8.3 °C | 1.1 °C | 43.94 mm |
| February | -6.3 °C | 3.8 °C | 49.78 mm |
| March | -0.7 °C | 10.5 °C | 64.52 mm |
| April | 5.3 °C | 17.6 °C | 102.62 mm |
| May | 11.7 °C | 23.2 °C | 135.64 mm |
| June | 17.1 °C | 28.3 °C | 124.97 mm |
| July | 19.1 °C | 30.4 °C | 105.16 mm |
| August | 17.8 °C | 29.4 °C | 99.06 mm |
| September | 13.1 °C | 26.1 °C | 93.73 mm |
| October | 6.6 °C | 18.9 °C | 81.79 mm |
| November | 0.3 °C | 10.8 °C | 66.8 mm |
| December | -5.2 °C | 3.8 °C | 49.78 mm |
| Annual | 5.9 °C | 17 °C | 1017.79 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 |