Glenn, Georgia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.1 °C (low) to 23.4 °C (high). Annual precipitation averages 1380.5 Millimeters. Glenn is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.1 °C | 12.9 °C | 135.13 mm |
| February | 1.8 °C | 15.2 °C | 133.1 mm |
| March | 5.1 °C | 19.5 °C | 132.08 mm |
| April | 8.8 °C | 23.9 °C | 115.57 mm |
| May | 13.9 °C | 27.8 °C | 98.3 mm |
| June | 18.3 °C | 30.9 °C | 116.84 mm |
| July | 20.3 °C | 32.5 °C | 126.75 mm |
| August | 19.9 °C | 31.8 °C | 106.43 mm |
| September | 16.5 °C | 29.3 °C | 93.98 mm |
| October | 10.1 °C | 24.2 °C | 82.04 mm |
| November | 4.3 °C | 18.6 °C | 106.43 mm |
| December | 1.6 °C | 14.2 °C | 133.86 mm |
| Annual | 10.1 °C | 23.4 °C | 1380.51 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |