Bertram, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 12.8 °C (low) to 25.2 °C (high). Annual precipitation averages 831.6 Millimeters. Bertram is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 1 - Mar. 10 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.7 °C | 15.2 °C | 53.59 mm |
| February | 4.6 °C | 17.1 °C | 48.01 mm |
| March | 8.3 °C | 21.1 °C | 69.85 mm |
| April | 12.2 °C | 25.2 °C | 61.98 mm |
| May | 17.2 °C | 28.6 °C | 109.22 mm |
| June | 20.9 °C | 32.4 °C | 81.03 mm |
| July | 22.2 °C | 34.2 °C | 50.8 mm |
| August | 22.1 °C | 34.9 °C | 52.83 mm |
| September | 18.9 °C | 31.3 °C | 84.58 mm |
| October | 13.4 °C | 26.3 °C | 90.17 mm |
| November | 7.8 °C | 20.2 °C | 69.6 mm |
| December | 3.3 °C | 15.8 °C | 59.94 mm |
| Annual | 12.8 °C | 25.2 °C | 831.6 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 1 - Mar. 10 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |