Calvert, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 13.7 °C (low) to 26 °C (high). Annual precipitation averages 1000.3 Millimeters. Calvert is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Feb. 21 - Feb. 29 through the first frost around Nov. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.7 °C | 15.8 °C | 85.09 mm |
| February | 5.7 °C | 17.8 °C | 71.63 mm |
| March | 9.2 °C | 21.7 °C | 85.6 mm |
| April | 13.1 °C | 25.8 °C | 76.2 mm |
| May | 18.2 °C | 29.6 °C | 115.06 mm |
| June | 21.9 °C | 33.2 °C | 85.85 mm |
| July | 23.1 °C | 35.1 °C | 46.48 mm |
| August | 22.8 °C | 35.6 °C | 67.31 mm |
| September | 19.7 °C | 32.5 °C | 85.09 mm |
| October | 14.1 °C | 27.3 °C | 109.73 mm |
| November | 8.6 °C | 21.2 °C | 81.03 mm |
| December | 4.6 °C | 16.7 °C | 91.19 mm |
| Annual | 13.7 °C | 26 °C | 1000.26 mm |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Feb. 21 - Feb. 29 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |