, according to the
Trewartha climate classification entrance to the
Chesapeake Bay Bridge–Tunnel in eastern
Pennsylvania with
Allentown in the foreground in December 2010 in
Adirondack Park in
Upstate New York in August 2007 In simplest terms, three (3) basic climate regions occur on the East Coast; 1) A cold continental climate, from the US-Canadian border south to southern Rhode Island and western Maryland, 2) a temperate climate, from coastal Rhode Island south to
western North Carolina, and 3) a subtropical climate from extreme southeast Virginia south to central Florida. The
humid continental climate region (
Dfa/Dfb/Dc) includes Maine, New Hampshire, Vermont, most of Massachusetts, most of Rhode Island, most of Connecticut, most of New York State, most of
North Jersey, most of Pennsylvania, and
western Maryland. This region features warm to occasionally hot summers and cold winters with frequent snow (especially in Maine, Vermont, and New Hampshire). All locations have a least one month with a mean temperature below 0 °C (32 °F) and four to seven months averaging above 10 °C (50 °F). The area from southern Rhode Island southward (coastal Connecticut,
Long Island,
New York City, most of New Jersey, most of Delaware, most of Maryland, most of Virginia, and western NC) has a warm
temperate climate (
Cfa/Do) with long, hot, humid summers and cool to cold winters with occasional snow. The mean temparature in the coldest month is 0 °C (32 °F) or higher. Normally, at least one month has a mean temperature over 22 °C (71.6 °F) and six to seven months average above 10 °C (50 °F).. The area from the southern
Delmarva Peninsula, southeast Virginia, and
central North Carolina south to central Florida is humid
subtropical (
Cfa/Cf), with hot summers that have almost daily (but brief) thundershowers and mild and drier winters. In this zone, at least eight months have a mean temperature above 10 °C (50 °F). The region of Florida from the south-central region of the state south to the
Florida Keys has a
tropical climate (
Af/Aw/Ar) that is usually frost-free and warm to hot all year, and all of the 12 months of the year average above 18 °C (64.4 °F). This region of Florida is the only tropical climate in the continental United States. The least common climate on the East Coast is the
oceanic (
Cfb/Do), which is only found on
Block Island,
Nantucket, and the Outer Cape and
Chatham on
Cape Cod, and in areas of the southern
Appalachian Mountains. This zone has all monthly averages between 0 and 22 °C and six to seven months above 50 °F. Although winter precipitation is more likely to fall as rain than as snow, occasional heavy snow is possible. Although landfalls are rare, the Eastern Seaboard is susceptible to
hurricanes in the Atlantic hurricane season, officially running from June 1 to November 30, although hurricanes can occur before or after these dates. Hurricanes
Hazel,
Hugo,
Bob,
Isabel,
Irene, and
Sandy, and most recently
Florence,
Isaias,
Henri, and
Ida are some of the more significant storms to have affected the region. The East Coast, with the exception of Eastern Maine, is a low relief,
passive margin coast. It has been shaped by the
Pleistocene glaciation in the far northern areas in New England, with offshore islands such as
Nantucket,
Martha's Vineyard,
Block Island, and
Fishers Island. From
northern New Jersey southward, the coastal plain broadens southwards, separated from the
Piedmont region by the
Atlantic Seaboard fall line of the East Coast rivers, often marking the head of navigation and prominent sites of cities. The coastal areas from
Long Island south to Florida are often made up of
barrier islands that front the coastal areas, with the long stretches of sandy beaches. Many of the larger capes along the lower East Coast are in fact barrier islands, like the
Outer Banks of North Carolina and
Cape Canaveral, Florida. The Florida Keys are made up of limestone coral and provide the only
coral reefs on the U.S. mainland. ==Demographics==