Green flags lined Fort Lauderdale Beach on Sunday, signaling calm conditions. But as Hurricane Erin approaches, officials say things could change in the coming days.

The Atlantic basin includes the northern Atlantic Ocean, Caribbean Sea and Gulf of America, as the Gulf of Mexico is now known in the U.S. per an order from President Trump. NOAA and the National Hurricane Center are now using Gulf of America on its maps and in its advisories.

Hurricane Erin was a Category 4 storm again Monday morning and is expected to grow even larger and stronger, according to the latest advisory from the National Hurricane Center. Although Erin is forecast to move north between the U.S. and Bermuda, life-threatening surf and rip currents are likely across the Atlantic coast from Florida to Canada.