Weldon, 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 16.7 °C (high). Annual precipitation averages 995.9 Millimeters. Weldon 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.1 °C | 0.9 °C | 56.9 mm |
| February | -6.3 °C | 3.4 °C | 50.29 mm |
| March | -1.3 °C | 9.9 °C | 68.58 mm |
| April | 4.8 °C | 17.6 °C | 100.33 mm |
| May | 11.3 °C | 23.3 °C | 113.79 mm |
| June | 16.3 °C | 28.2 °C | 115.82 mm |
| July | 18 °C | 29.6 °C | 103.12 mm |
| August | 16.8 °C | 28.7 °C | 85.6 mm |
| September | 12.6 °C | 26.1 °C | 81.53 mm |
| October | 5.9 °C | 18.8 °C | 84.84 mm |
| November | 0 °C | 10.6 °C | 74.42 mm |
| December | -4.9 °C | 3.6 °C | 60.71 mm |
| Annual | 5.4 °C | 16.7 °C | 995.93 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 |