The National Weather Service says more than 5.4 million people live in areas now under hurricane warnings or watches on the U.S. East Coast.
Another 4 million people are under a tropical storm watch. Assorted bad weather advisories stretched from Florida to Maine on Tuesday evening.
Those facing the most serious threat are in the Carolinas, as Category 4 Hurricane Florence barrels toward the coast, with an expected landfall Friday.
The National Hurricane Center in Miami said Tuesday that a hurricane warning had been issued from South Santee River, South Carolina, to Duck, North Carolina, and the Albemarle and Pamlico Sounds.
A Tropical Storm Watch has been issued from north of the North Carolina-Virginia border to Cape Charles Light, Virginia, and for the Chesapeake Bay south of New Point Comfort.
WATCH: Time-lapse video of a Hurricane Hunter flight going into Hurricane Florence Monday.
Time-lapse video of a #NOAA WP-3D Hurricane Hunter (#NOAA42) flight into Hurricane #Florence on Sept. 10, 2018. Get the latest on the storm at https://t.co/MlZk25kG0d. Credit: Nick Underwood/NOAA pic.twitter.com/FQ3RJMKVUU
— NOAA Aircraft Operations Center (@NOAA_HurrHunter) September 11, 2018