Granjeno, Texas has a Hot Semi-Arid Climate climate (Köppen classification: BSh). Average annual temperatures range from 18 °C (low) to 29.9 °C (high). Annual precipitation averages 548.1 Millimeters. Granjeno is located in USDA Plant Hardiness Zone 10a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 9.7 °C | 21.7 °C | 20.57 mm |
| February | 11.9 °C | 24.3 °C | 23.62 mm |
| March | 15.1 °C | 27.2 °C | 29.21 mm |
| April | 18.3 °C | 30.4 °C | 34.29 mm |
| May | 21.9 °C | 33.1 °C | 54.61 mm |
| June | 24 °C | 35.6 °C | 63.5 mm |
| July | 24.6 °C | 36.2 °C | 56.13 mm |
| August | 24.6 °C | 36.8 °C | 38.86 mm |
| September | 22.7 °C | 34 °C | 117.6 mm |
| October | 18.7 °C | 31.2 °C | 57.4 mm |
| November | 14.1 °C | 26.3 °C | 29.97 mm |
| December | 10.5 °C | 22.5 °C | 22.35 mm |
| Annual | 18 °C | 29.9 °C | 548.11 mm |
| Average First Frost Date | No Frost |
| Average Last Frost Date | |
| Average Days With Frost | Frost Free |
| Plant Hardiness Zone | Zone 10a : -1.1°C to 1.7°C |
| Plant Hardiness Zone - 2012 | Zone 9b : -3.9°C to -1.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | BSh - Hot Semi-Arid Climate |