Algonquin, Maryland has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 9.5 °C (low) to 19.2 °C (high). Annual precipitation averages 1163.6 Millimeters. Algonquin is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -1.6 °C | 6.9 °C | 85.34 mm |
| February | -1.1 °C | 8.3 °C | 72.14 mm |
| March | 2.7 °C | 12.5 °C | 107.95 mm |
| April | 8.2 °C | 19 °C | 85.34 mm |
| May | 13.4 °C | 23.7 °C | 98.3 mm |
| June | 18.6 °C | 28.4 °C | 98.81 mm |
| July | 21.3 °C | 30.9 °C | 118.36 mm |
| August | 20.3 °C | 29.8 °C | 115.82 mm |
| September | 16.7 °C | 26.6 °C | 103.63 mm |
| October | 10.4 °C | 20.7 °C | 98.81 mm |
| November | 4.8 °C | 14.6 °C | 83.57 mm |
| December | 0.8 °C | 9.3 °C | 95.5 mm |
| Annual | 9.5 °C | 19.2 °C | 1163.57 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |