Portsmouth, Virginia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 52.6 °F (low) to 69.9 °F (high). Annual precipitation averages 50.5 Inches. Portsmouth is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 33.4 °F | 50.8 °F | 3.56 in. |
| February | 34.7 °F | 53.3 °F | 2.83 in. |
| March | 41.1 °F | 59.7 °F | 3.97 in. |
| April | 50.3 °F | 69.4 °F | 3.61 in. |
| May | 59.1 °F | 76.9 °F | 4.23 in. |
| June | 67.7 °F | 84.2 °F | 4.79 in. |
| July | 72.2 °F | 88.5 °F | 5.36 in. |
| August | 70.9 °F | 86.5 °F | 5.68 in. |
| September | 66.1 °F | 81.1 °F | 5.38 in. |
| October | 54.7 °F | 71.7 °F | 4.16 in. |
| November | 43.9 °F | 62.2 °F | 3.37 in. |
| December | 37.4 °F | 54.5 °F | 3.58 in. |
| Annual | 52.6 °F | 69.9 °F | 50.52 in. |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8a : 10°F to 15°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |