Harper, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 52.9 °F (low) to 76 °F (high). Annual precipitation averages 28.5 Inches. Harper 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 | 35.0 °F | 58.9 °F | 1.53 in. |
| February | 38.3 °F | 62.8 °F | 1.55 in. |
| March | 45.6 °F | 69.3 °F | 2.49 in. |
| April | 52.2 °F | 76.0 °F | 2.11 in. |
| May | 60.7 °F | 82.3 °F | 4.06 in. |
| June | 67.0 °F | 88.5 °F | 3.05 in. |
| July | 68.9 °F | 91.3 °F | 1.78 in. |
| August | 68.5 °F | 92.2 °F | 2.09 in. |
| September | 62.9 °F | 85.8 °F | 3.31 in. |
| October | 54.5 °F | 77.8 °F | 2.78 in. |
| November | 44.5 °F | 67.0 °F | 2.14 in. |
| December | 36.5 °F | 59.6 °F | 1.64 in. |
| Annual | 52.9 °F | 76 °F | 28.53 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| 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 8a : 10°F to 15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |