Olney, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 45.5 °F (low) to 64.6 °F (high). Annual precipitation averages 46.1 Inches. Olney is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 25.1 °F | 41.6 °F | 3.19 in. |
| February | 26.6 °F | 44.7 °F | 2.84 in. |
| March | 33.4 °F | 53.2 °F | 4.06 in. |
| April | 43.3 °F | 65.2 °F | 3.54 in. |
| May | 53.2 °F | 73.6 °F | 4.5 in. |
| June | 61.8 °F | 81.9 °F | 4.51 in. |
| July | 66.4 °F | 86.1 °F | 4.34 in. |
| August | 64.7 °F | 84.2 °F | 3.74 in. |
| September | 58.3 °F | 77.6 °F | 4.46 in. |
| October | 46.5 °F | 66.1 °F | 3.94 in. |
| November | 36.6 °F | 55.4 °F | 3.27 in. |
| December | 29.5 °F | 45.5 °F | 3.75 in. |
| Annual | 45.5 °F | 64.6 °F | 46.14 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : 5°F to 10°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |