Garrison, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 54.4 °F (low) to 77.3 °F (high). Annual precipitation averages 51.8 Inches. Garrison is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 35.9 °F | 58.4 °F | 4.7 in. |
| February | 39.5 °F | 62.8 °F | 4.13 in. |
| March | 46.2 °F | 69.9 °F | 4.68 in. |
| April | 53.0 °F | 77.2 °F | 4.66 in. |
| May | 62.6 °F | 84.2 °F | 4.44 in. |
| June | 69.7 °F | 90.5 °F | 4.73 in. |
| July | 72.4 °F | 93.8 °F | 3.08 in. |
| August | 71.7 °F | 94.7 °F | 3.48 in. |
| September | 65.4 °F | 88.9 °F | 3.81 in. |
| October | 54.4 °F | 79.4 °F | 4.52 in. |
| November | 44.4 °F | 68.0 °F | 4.5 in. |
| December | 37.7 °F | 60.1 °F | 5.11 in. |
| Annual | 54.4 °F | 77.3 °F | 51.84 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |