Riverdale, Georgia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.9 °C (low) to 22.5 °C (high). Annual precipitation averages 1337 Millimeters. Riverdale is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.6 °C | 11.9 °C | 123.95 mm |
| February | 2.2 °C | 14.1 °C | 123.7 mm |
| March | 5.9 °C | 18.5 °C | 127.51 mm |
| April | 10 °C | 22.8 °C | 106.93 mm |
| May | 15.2 °C | 26.9 °C | 90.17 mm |
| June | 19.3 °C | 30.2 °C | 111 mm |
| July | 21.2 °C | 31.9 °C | 129.03 mm |
| August | 20.7 °C | 31.3 °C | 110.74 mm |
| September | 17.6 °C | 28.4 °C | 97.28 mm |
| October | 11.2 °C | 23.2 °C | 89.15 mm |
| November | 5.1 °C | 17.7 °C | 104.14 mm |
| December | 2.2 °C | 13.3 °C | 123.44 mm |
| Annual | 10.9 °C | 22.5 °C | 1337.04 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |