Justin, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 54.9 °F (low) to 76.7 °F (high). Annual precipitation averages 38.2 Inches. Justin 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 | 34.2 °F | 56.4 °F | 2.26 in. |
| February | 37.7 °F | 60.0 °F | 2.56 in. |
| March | 45.6 °F | 68.0 °F | 3.52 in. |
| April | 53.4 °F | 75.8 °F | 3.67 in. |
| May | 63.1 °F | 83.2 °F | 4.57 in. |
| June | 71.4 °F | 91.6 °F | 3.99 in. |
| July | 74.9 °F | 95.8 °F | 2.09 in. |
| August | 74.5 °F | 96.4 °F | 2.43 in. |
| September | 66.9 °F | 89.1 °F | 3.12 in. |
| October | 55.4 °F | 78.6 °F | 4.25 in. |
| November | 45.0 °F | 67.0 °F | 2.87 in. |
| December | 36.1 °F | 57.9 °F | 2.87 in. |
| Annual | 54.9 °F | 76.7 °F | 38.2 in. |
| 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 : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8a : 10°F to 15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |