Bartelso, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.4 °C (low) to 18.6 °C (high). Annual precipitation averages 1103.9 Millimeters. Bartelso is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.6 °C | 3.8 °C | 70.61 mm |
| February | -3.9 °C | 6.7 °C | 60.71 mm |
| March | 1.4 °C | 12.5 °C | 86.36 mm |
| April | 7.1 °C | 19.3 °C | 120.14 mm |
| May | 13.1 °C | 24.3 °C | 127 mm |
| June | 18.1 °C | 29.3 °C | 123.95 mm |
| July | 19.9 °C | 31.1 °C | 101.6 mm |
| August | 18.7 °C | 30.7 °C | 82.55 mm |
| September | 14 °C | 26.8 °C | 84.84 mm |
| October | 7.4 °C | 20.3 °C | 81.03 mm |
| November | 1.7 °C | 12.5 °C | 93.22 mm |
| December | -3.2 °C | 6.3 °C | 71.88 mm |
| Annual | 7.4 °C | 18.6 °C | 1103.89 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°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 |