Port Royal, Virginia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.3 °C (low) to 20.1 °C (high). Annual precipitation averages 1132.1 Millimeters. Port Royal is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.3 °C | 7.9 °C | 79.5 mm |
| February | -1.6 °C | 9.7 °C | 69.6 mm |
| March | 2.1 °C | 14.1 °C | 98.3 mm |
| April | 6.8 °C | 19.3 °C | 83.57 mm |
| May | 12.3 °C | 24.8 °C | 101.85 mm |
| June | 17.5 °C | 29.3 °C | 107.44 mm |
| July | 20.1 °C | 31.7 °C | 111 mm |
| August | 18.2 °C | 30.5 °C | 102.62 mm |
| September | 15.5 °C | 27.1 °C | 109.47 mm |
| October | 8.8 °C | 21.2 °C | 93.98 mm |
| November | 3.1 °C | 15.1 °C | 82.3 mm |
| December | -0.6 °C | 10.1 °C | 92.46 mm |
| Annual | 8.3 °C | 20.1 °C | 1132.09 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |