Merkel, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 11.1 °C (low) to 24.8 °C (high). Annual precipitation averages 645.9 Millimeters. Merkel 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 | -0.3 °C | 13.8 °C | 26.92 mm |
| February | 1.7 °C | 16.1 °C | 36.83 mm |
| March | 5.9 °C | 20.6 °C | 48.51 mm |
| April | 10.2 °C | 25.2 °C | 46.74 mm |
| May | 15.8 °C | 29.3 °C | 83.57 mm |
| June | 20.3 °C | 33 °C | 77.47 mm |
| July | 22.1 °C | 34.9 °C | 53.59 mm |
| August | 21.8 °C | 34.8 °C | 59.69 mm |
| September | 17.6 °C | 30.6 °C | 77.98 mm |
| October | 11.7 °C | 25.6 °C | 64.01 mm |
| November | 5.3 °C | 19.1 °C | 39.62 mm |
| December | 0.8 °C | 14.4 °C | 30.99 mm |
| Annual | 11.1 °C | 24.8 °C | 645.92 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |