Centralia, 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 18.5 °C (high). Annual precipitation averages 1141.5 Millimeters. Centralia 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 | -5.3 °C | 3.8 °C | 76.71 mm |
| February | -3.5 °C | 6.5 °C | 65.28 mm |
| March | 1.4 °C | 12.3 °C | 93.98 mm |
| April | 7.1 °C | 19 °C | 123.44 mm |
| May | 13.1 °C | 24.2 °C | 127.51 mm |
| June | 17.9 °C | 29.2 °C | 123.7 mm |
| July | 19.8 °C | 30.9 °C | 102.36 mm |
| August | 18.4 °C | 30.4 °C | 82.04 mm |
| September | 13.8 °C | 26.9 °C | 86.36 mm |
| October | 7.4 °C | 20.6 °C | 86.61 mm |
| November | 1.8 °C | 12.5 °C | 97.54 mm |
| December | -2.8 °C | 6.2 °C | 75.95 mm |
| Annual | 7.4 °C | 18.5 °C | 1141.48 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 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 |