Olney, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.9 °C (low) to 25 °C (high). Annual precipitation averages 780.3 Millimeters. Olney is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -0.8 °C | 13.4 °C | 35.56 mm |
| February | 1 °C | 15.4 °C | 41.66 mm |
| March | 5.6 °C | 20.4 °C | 59.69 mm |
| April | 9.8 °C | 25.2 °C | 64.52 mm |
| May | 15.5 °C | 29.2 °C | 121.67 mm |
| June | 20.5 °C | 33.3 °C | 92.96 mm |
| July | 22.6 °C | 36.1 °C | 66.04 mm |
| August | 22.1 °C | 36.1 °C | 51.56 mm |
| September | 17.8 °C | 31.8 °C | 75.69 mm |
| October | 11.6 °C | 26.1 °C | 82.04 mm |
| November | 5.1 °C | 19.2 °C | 48.01 mm |
| December | 0.3 °C | 14.1 °C | 40.89 mm |
| Annual | 10.9 °C | 25 °C | 780.29 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |