Festus, Missouri has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.3 °C (low) to 19.4 °C (high). Annual precipitation averages 1105.2 Millimeters. Festus is located in USDA Plant Hardiness Zone 7a. 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 | -4.7 °C | 4.9 °C | 69.6 mm |
| February | -2.7 °C | 7.9 °C | 62.74 mm |
| March | 2 °C | 13.3 °C | 100.08 mm |
| April | 7.8 °C | 19.9 °C | 127.51 mm |
| May | 13.7 °C | 25 °C | 121.67 mm |
| June | 18.6 °C | 29.8 °C | 108.71 mm |
| July | 20.8 °C | 31.7 °C | 102.36 mm |
| August | 19.7 °C | 30.9 °C | 90.17 mm |
| September | 15.2 °C | 27.4 °C | 86.61 mm |
| October | 8.6 °C | 21 °C | 76.2 mm |
| November | 2.7 °C | 13.4 °C | 86.87 mm |
| December | -2.2 °C | 7.2 °C | 72.64 mm |
| Annual | 8.3 °C | 19.4 °C | 1105.16 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 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |