Three flags warn of surf and rip current conditions. Red means a high hazard, yellow means a moderate threat and green means low danger. There's also purple for dangerous sea life, such as jellyfish, and double red when a beach is closed for any reason.

Hurricane Erin won't make landfall in the U.S., but it will bring dangerous rip currents to the East Coast. Beachgoers from Florida to the Carolinas to the Mid-Atlantic to Long Island need to be on alert for rip currents from Erin this week. Here's what you need to know about rip currents and how to stay safe:

Hurricane Erin will be hundreds of miles from the Massachusetts coast, but it could still cause problems at beaches.