San Isidro, Texas has a Hot Semi-Arid Climate climate (Köppen classification: BSh). Average annual temperatures range from 62.7 °F (low) to 86.1 °F (high). Annual precipitation averages 22.5 Inches. San Isidro is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Jan. 21 - Jan. 31 through the first frost around Dec. 21 - Dec. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 47.0 °F | 70.8 °F | 1.0 in. |
| February | 51.5 °F | 75.6 °F | 0.98 in. |
| March | 57.5 °F | 81.6 °F | 1.14 in. |
| April | 63.7 °F | 86.8 °F | 1.35 in. |
| May | 70.1 °F | 92.7 °F | 2.58 in. |
| June | 73.7 °F | 97.2 °F | 2.49 in. |
| July | 74.8 °F | 98.0 °F | 2.29 in. |
| August | 74.4 °F | 98.8 °F | 1.54 in. |
| September | 71.1 °F | 93.1 °F | 4.41 in. |
| October | 63.7 °F | 88.1 °F | 2.36 in. |
| November | 55.0 °F | 79.1 °F | 1.29 in. |
| December | 49.5 °F | 71.5 °F | 1.05 in. |
| Annual | 62.7 °F | 86.1 °F | 22.48 in. |
| Average First Frost Date | Dec. 21 - Dec. 31 |
| Average Last Frost Date | Jan. 21 - Jan. 31 |
| Average Days With Frost | Frost Rare |
| Plant Hardiness Zone | Zone 9b : 25°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 9b : 25°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | BSh - Hot Semi-Arid Climate |