Olmito, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 18.5 °C (low) to 29 °C (high). Annual precipitation averages 727.5 Millimeters. Olmito is located in USDA Plant Hardiness Zone 10a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 10.5 °C | 21.3 °C | 29.21 mm |
| February | 12.6 °C | 23.6 °C | 34.54 mm |
| March | 15.5 °C | 26.3 °C | 35.05 mm |
| April | 18.8 °C | 29.2 °C | 38.1 mm |
| May | 22.2 °C | 31.9 °C | 59.18 mm |
| June | 24.3 °C | 34.2 °C | 69.85 mm |
| July | 24.7 °C | 34.7 °C | 70.61 mm |
| August | 24.8 °C | 35.4 °C | 51.56 mm |
| September | 23 °C | 33 °C | 149.35 mm |
| October | 19.2 °C | 30.3 °C | 99.57 mm |
| November | 14.7 °C | 25.8 °C | 47.5 mm |
| December | 11.2 °C | 22.1 °C | 42.93 mm |
| Annual | 18.5 °C | 29 °C | 727.45 mm |
| Average First Frost Date | Frost Rare |
| 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 10a : -1.1°C to 1.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |