Florissant, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 8.8 °C (low) to 19 °C (high). Annual precipitation averages 1092.4 Millimeters. Florissant 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 Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.4 °C | 4.3 °C | 67.06 mm |
| February | -2.7 °C | 7.4 °C | 55.88 mm |
| March | 2.3 °C | 13.2 °C | 87.12 mm |
| April | 8.3 °C | 19.7 °C | 123.7 mm |
| May | 14.3 °C | 24.7 °C | 128.52 mm |
| June | 19.4 °C | 29.6 °C | 117.09 mm |
| July | 21.4 °C | 31.3 °C | 99.57 mm |
| August | 20.4 °C | 30.8 °C | 90.93 mm |
| September | 15.8 °C | 27 °C | 81.28 mm |
| October | 9.4 °C | 20.7 °C | 82.8 mm |
| November | 2.9 °C | 12.8 °C | 89.66 mm |
| December | -1.8 °C | 6.8 °C | 68.83 mm |
| Annual | 8.8 °C | 19 °C | 1092.44 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| 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 | Dfa - Humid Continental Hot Summers With Year Around Precipitation |