The Florida Highway Patrol closed the Courtney Campbell Parkway shortly before 3 p.m., officials in the Pinellas County emergency operation center said.
The decision was made after a Clearwater police officer drove across and observed the wind tugging at the windshield wipers on his car, Pinellas spokeswoman Marcia Crawley said.
Meanwhile, Belleair Causeway, which was shut down earlier because of a power line, is now cleared and open.
Progress Energy reported about 80,000 homes without power in Pinellas and officials say their workers are unlikely to fix any until the winds calm down.