Granjeno, Texas has a Hot Semi-Arid Climate climate (Köppen classification: BSh). Average annual temperatures range from 64.4 °F (low) to 85.9 °F (high). Annual precipitation averages 21.6 Inches. Granjeno is located in USDA Plant Hardiness Zone 10a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 49.5 °F | 71.1 °F | 0.81 in. |
| February | 53.5 °F | 75.7 °F | 0.93 in. |
| March | 59.1 °F | 80.9 °F | 1.15 in. |
| April | 65.0 °F | 86.8 °F | 1.35 in. |
| May | 71.4 °F | 91.6 °F | 2.15 in. |
| June | 75.2 °F | 96.1 °F | 2.5 in. |
| July | 76.2 °F | 97.1 °F | 2.21 in. |
| August | 76.2 °F | 98.3 °F | 1.53 in. |
| September | 72.8 °F | 93.2 °F | 4.63 in. |
| October | 65.7 °F | 88.1 °F | 2.26 in. |
| November | 57.3 °F | 79.3 °F | 1.18 in. |
| December | 50.9 °F | 72.5 °F | 0.88 in. |
| Annual | 64.4 °F | 85.9 °F | 21.58 in. |
| Average First Frost Date | No Frost |
| Average Last Frost Date | |
| Average Days With Frost | Frost Free |
| Plant Hardiness Zone | Zone 10a : 30°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 9b : 25°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | BSh - Hot Semi-Arid Climate |