Onley, Virginia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.2 °C (low) to 19.6 °C (high). Annual precipitation averages 1194.1 Millimeters. Onley 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. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -0.7 °C | 8.6 °C | 86.87 mm |
| February | -0.1 °C | 9.7 °C | 76.71 mm |
| March | 3.3 °C | 13 °C | 103.63 mm |
| April | 8.7 °C | 18.6 °C | 86.87 mm |
| May | 14 °C | 23.4 °C | 91.95 mm |
| June | 18.9 °C | 28.1 °C | 104.9 mm |
| July | 21.7 °C | 30.5 °C | 117.35 mm |
| August | 20.6 °C | 29.3 °C | 118.62 mm |
| September | 17.6 °C | 26.4 °C | 104.65 mm |
| October | 11.4 °C | 21.1 °C | 114.55 mm |
| November | 5.5 °C | 15.3 °C | 89.66 mm |
| December | 1.7 °C | 10.9 °C | 98.3 mm |
| Annual | 10.2 °C | 19.6 °C | 1194.06 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| 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 | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |