Brenham, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 14.4 °C (low) to 26.3 °C (high). Annual precipitation averages 1161.3 Millimeters. Brenham 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 Dec. 1 - Dec. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 4.7 °C | 16.4 °C | 91.19 mm |
| February | 6.7 °C | 18.4 °C | 80.77 mm |
| March | 10.4 °C | 22.1 °C | 89.41 mm |
| April | 14.1 °C | 26.1 °C | 83.31 mm |
| May | 18.6 °C | 29.8 °C | 131.83 mm |
| June | 22.1 °C | 33.2 °C | 112.01 mm |
| July | 23.2 °C | 34.7 °C | 64.26 mm |
| August | 23.1 °C | 35.7 °C | 86.36 mm |
| September | 20.3 °C | 32.6 °C | 99.06 mm |
| October | 14.8 °C | 27.8 °C | 126.49 mm |
| November | 9.3 °C | 21.7 °C | 104.65 mm |
| December | 5.6 °C | 17.4 °C | 91.95 mm |
| Annual | 14.4 °C | 26.3 °C | 1161.29 mm |
| Average First Frost Date | Dec. 1 - Dec. 10 |
| Average Last Frost Date | Feb. 21 - Feb. 29 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°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 |