Alpharetta, Georgia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 49.5 °F (low) to 70.9 °F (high). Annual precipitation averages 54 Inches. Alpharetta 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. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 30.8 °F | 51.0 °F | 4.96 in. |
| February | 33.6 °F | 55.2 °F | 4.85 in. |
| March | 39.9 °F | 63.4 °F | 5.12 in. |
| April | 47.6 °F | 71.8 °F | 4.33 in. |
| May | 56.9 °F | 78.9 °F | 4.0 in. |
| June | 64.9 °F | 85.0 °F | 4.29 in. |
| July | 68.4 °F | 87.9 °F | 5.03 in. |
| August | 67.6 °F | 87.5 °F | 4.25 in. |
| September | 61.4 °F | 82.2 °F | 4.43 in. |
| October | 49.8 °F | 72.5 °F | 3.72 in. |
| November | 38.9 °F | 61.9 °F | 4.26 in. |
| December | 33.9 °F | 53.6 °F | 4.71 in. |
| Annual | 49.5 °F | 70.9 °F | 53.95 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8a : 10°F to 15°F |
| Plant Hardiness Zone - 2012 | Zone 7b : 5°F to 10°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |