More than 33 million Americans were under coastal flood advisories on Wednesday, Aug 20 as Hurricane Erin continues to bring big waves and higher tides to much of the East Coast.

Coastal floods - European Commission

Nearly 8 million people are currently under coastal flood warnings across the United States, according to a map provided by the National Weather Service.

The graphic shows light and dark green notices, signaling coastal flood advisories and warnings, along the coast.

Forecasters have warned that significant coastal erosion, with waves reaching heights of 15 to 20 feet and a storm surge of up to four feet, could hit North Carolina beaches the hardest through at least Thursday, Aug. 21.

The National Hurricane Center is strongly discouraging swimming at most East Coast beaches, particularly the North Carolina Outer Banks, as Erin nears.

Coastal Flooding | What Causes it?

Erin was classified as a Category 2 hurricane on Aug. 20, nearing Category 3 status with sustained winds of 110 mph, the NHC reported.

The storm was located about 295 miles south-southeast of Cape Hatteras, North Carolina, and heading north at 14 mph, prompting a tropical storm warning for parts of North Carolina and Virginia.

The center forecasts the system to continue heading north and is expected to make its closest approach to the mainland by early Aug. 21, while remaining hundreds of miles offshore.