Kemah, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 17.6 °C (low) to 25.1 °C (high). Annual precipitation averages 1498.3 Millimeters. Kemah is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 8.3 °C | 16.4 °C | 118.11 mm |
| February | 10.2 °C | 18.2 °C | 80.01 mm |
| March | 13.7 °C | 21.3 °C | 85.85 mm |
| April | 17.3 °C | 24.6 °C | 112.27 mm |
| May | 21.5 °C | 28.2 °C | 130.3 mm |
| June | 24.7 °C | 31.2 °C | 151.89 mm |
| July | 25.5 °C | 32.3 °C | 116.33 mm |
| August | 25.2 °C | 32.7 °C | 163.58 mm |
| September | 23.4 °C | 30.6 °C | 160.02 mm |
| October | 19.2 °C | 26.6 °C | 141.22 mm |
| November | 13.5 °C | 21.4 °C | 123.19 mm |
| December | 9.2 °C | 17.5 °C | 115.57 mm |
| Annual | 17.6 °C | 25.1 °C | 1498.34 mm |
| Average First Frost Date | Frost Rare |
| Average Last Frost Date | |
| Average Days With Frost | Frost Rare |
| Plant Hardiness Zone | Zone 9b : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |