Timonium, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.6 °C (low) to 18.6 °C (high). Annual precipitation averages 1236.2 Millimeters. Timonium 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 | -4 °C | 5.7 °C | 87.63 mm |
| February | -3.2 °C | 7.2 °C | 74.68 mm |
| March | 0.6 °C | 11.9 °C | 109.47 mm |
| April | 6.4 °C | 18.6 °C | 96.77 mm |
| May | 11.8 °C | 23.6 °C | 109.47 mm |
| June | 16.8 °C | 28.3 °C | 109.22 mm |
| July | 19.6 °C | 30.8 °C | 114.3 mm |
| August | 18.6 °C | 29.8 °C | 106.68 mm |
| September | 14.8 °C | 26 °C | 121.41 mm |
| October | 8.3 °C | 19.7 °C | 114.05 mm |
| November | 2.6 °C | 13.4 °C | 87.88 mm |
| December | -1.4 °C | 7.9 °C | 104.65 mm |
| Annual | 7.6 °C | 18.6 °C | 1236.21 mm |
| 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 : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |