Hurricane Idalia came ashore last August some 200 miles north of Jennifer Connell-Wandstrat’s neighborhood in St. Petersburg, Fla., but her ranch-style home flooded with nine inches of water that ruined her appliances, doors, dry wall, floors and furniture. She still sleeps on a mattress on the living room floor with her youngest daughter.

Such an ordeal might have once seemed unlikely to ever happen again, at least in a resident’s lifetime. But Ms. Connell-Wandstrat is under no such illusion.

She lives in Shore Acres, a low-lying enclave at the edge of Tampa Bay where streets are broad, homes are comfortable — and floodwater has become a constant threat.

“Now it’s a real fear,” said Ms. Connell-Wandstrat, whose home has flooded twice in three years. “When’s it going to happen next?”

The next hugely damaging storm surge is only a matter of time, she and her neighbors know, especially with forecasters expecting the hurricane season that began on Saturday to be extraordinarily busy. Experts predict there will be 17 to 25 named storms, including four to seven that become major hurricanes with winds of at least 111 miles per hour.

Hurricane Idalia, while not as bad as other recent storms, inundated many neighborhoods far from the strong winds at its center. As climate change leads to higher sea levels and more frequent and intense storms, many more neighborhoods in Florida are expected to become vulnerable to flood risk. In Shore Acres, at least 1,200 of the roughly 2,600 homes flooded with Idalia; many flooded again during a storm in December.