at most states of the tide. The limits of the island are not precisely determined and have varied over time. Older maps use the term for the island between Ocracoke Inlet and Whalebone Inlet (which closed in 1961, now the northern end of North Core Banks.) Climate According to the Trewartha climate classification system, Portsmouth, North Carolina has a humid subtropical climate with hot and humid summers, cool winters and year-around precipitation (Cfak). Cfak climates are characterized by all months having an average mean temperature > 32.0 °F (> 0.0 °C), at least eight months with an average mean temperature ≥ 50.0 °F (≥ 10.0 °C), at least one month with an average mean temperature ≥ 71.6 °F (≥ 22.0 °C) and no significant precipitation difference between seasons. During the summer months in Portsmouth, a cooling afternoon sea breeze is present on most days, but episodes of extreme heat and humidity can occur with heat index values ≥ 100 °F (≥ 38 °C). Portsmouth is prone to hurricane strikes, particularly during the Atlantic hurricane season which extends from June 1 through November 30, sharply peaking from late August through September. During the winter months, episodes of cold and wind can occur with wind chill values < 15 °F (< -9 °C). The plant hardiness zone in Portsmouth is 8b with an average annual extreme minimum air temperature of 17.5 °F (-8.1 °C). The average seasonal (Dec-Mar) snowfall total is < 2 inches (< 5 cm), and the average annual peak in nor'easter activity is in February. Ecology According to the A. W. Kuchler U.S. potential natural vegetation types, Portsmouth, North Carolina would have a dominant vegetation type of Live oak/Sea Oats Uniola paniculata (90) with a dominant vegetation form of Coastal Prairie (20). References External links National Park Service site A Home Transformed: Narratives of Home, Loss, Longing and the Miniature from Portsmouth Island, North Carolina (M.A. thesis in Folklore, University of North Carolina-Chapel Hill, 2009). Online resource. Portsmouth Island Ferry Google map of the island Portsmouth Island Vehicle and Passenger Ferry Outer Banks Beaches of North Carolina Ghost towns in North Carolina Geography of Carteret County, North Carolina Buildings and structures in Carteret County, North Carolina National Register of Historic Places in Carteret County, North Carolina Landforms of Carteret County, North Carolina Historic districts on the National Register of Historic Places in North Carolina Populated places on the National