Karnes City, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 58.9 °F (low) to 82 °F (high). Annual precipitation averages 30.7 Inches. Karnes City is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Frost Rare through the first frost around Jan. 11 - Jan. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 41.7 °F | 65.2 °F | 1.63 in. |
| February | 45.9 °F | 69.5 °F | 1.65 in. |
| March | 52.4 °F | 75.3 °F | 2.42 in. |
| April | 58.2 °F | 81.7 °F | 2.41 in. |
| May | 66.7 °F | 88.1 °F | 3.5 in. |
| June | 72.0 °F | 93.4 °F | 3.23 in. |
| July | 73.6 °F | 95.9 °F | 2.62 in. |
| August | 73.3 °F | 97.1 °F | 2.31 in. |
| September | 69.0 °F | 91.4 °F | 3.88 in. |
| October | 60.2 °F | 84.7 °F | 2.87 in. |
| November | 50.7 °F | 74.6 °F | 2.1 in. |
| December | 43.5 °F | 67.0 °F | 2.05 in. |
| Annual | 58.9 °F | 82 °F | 30.67 in. |
| Average First Frost Date | Jan. 11 - Jan. 20 |
| Average Last Frost Date | Frost Rare |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9a : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 9a : 20°F to 25°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |