Harrison, Tennessee has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 49.3 °F (low) to 71.2 °F (high). Annual precipitation averages 59.2 Inches. Harrison 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 | 30.1 °F | 49.8 °F | 5.74 in. |
| February | 33.0 °F | 54.3 °F | 5.34 in. |
| March | 39.6 °F | 62.9 °F | 5.6 in. |
| April | 47.8 °F | 72.2 °F | 4.83 in. |
| May | 57.2 °F | 79.6 °F | 4.3 in. |
| June | 65.4 °F | 86.2 °F | 4.6 in. |
| July | 69.2 °F | 89.2 °F | 5.44 in. |
| August | 68.2 °F | 88.8 °F | 4.09 in. |
| September | 61.7 °F | 83.7 °F | 4.9 in. |
| October | 49.1 °F | 73.2 °F | 3.38 in. |
| November | 37.6 °F | 61.6 °F | 4.94 in. |
| December | 32.9 °F | 52.6 °F | 6.08 in. |
| Annual | 49.3 °F | 71.2 °F | 59.24 in. |
| 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 : 10°F to 15°F |
| Plant Hardiness Zone - 2012 | Zone 7b : 5°F to 10°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |