Rough surf conditions and dangerous rip currents have forced many beaches to ban swimming and boogie boarding this week.

Hurricane Erin has strengthened to a Category 4 storm as it threatens to bring life-threatening surf and rip currents to the eastern coast of the United States. The rains caused by the storm are already beginning to hit the south-eastern Bahamas, and the Turk and Caicos Islands, where a tropical storm warning is in effect.

Forecasts nudge Erin's likely path to the west, increasing the risks at U.S. beaches. Experts say the storm's massive size, rather than windspeed, is what makes it a threat.

Two more tropical systems trail Hurricane Erin, which is following a projected course that brushes past the East Coast without making landfall.

Hundreds of thousands of beachgoing tourists were keeping a watchful eye on massive Hurricane Erin on Tuesday, Aug. 19, as large waves and rough surf driven by the powerful storm were taking aim at the Atlantic Coast from central Florida to Canada.

Hurricane Erin is expected to impact the Outer Banks in North Carolina, sending massive waves crashing into the barrier islands.

The hurricane’s behavior in recent days makes it one of the fastest-strengthening Atlantic hurricanes on record.

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