As anxious Florida residents watched weather forecasts this week, it seemed clear Hurricane Irma was on track to strike Miami, Fort Lauderdale and other Atlantic coast cities, prompting a massive evacuation.

But on Saturday, all that changed when Irma’s course shifted.

By Sunday morning, the Tampa-St.Petersburg area — once thought to be relatively safe from harm — suddenly found itself in the storm’s crosshairs.

“We know that we are ground zero for Hurricane Irma,” Tampa mayor Bob Buckhorn said at a Sunday morning news conference. “We have for 90 years avoided this day, but I think our day has come.”

The last time Tampa was hit by a major hurricane was in 1921.

Buckhorn quoted boxer Mike Tyson, saying, “Everybody has a plan until they get punched in the face.”

“Well,” he added, “we’re about to get punched in the face.”

Forecast models had anticipated Irma turning north earlier than it did, said CNN meteorologist Judson Jones. That would have put the hurricane over the east coast of Florida.

“What happened was the storm continued — after interacting with Cuba — to move west-northwest,” Jones said. “It took longer to make that turn to the north that we started to see more over the last 12 hours.”

Jones warned that some Floridians “may not have power for a number of days, if not weeks.”

Irma’s threat prompted Tampa officials to order a 6 p.m. curfew for Sunday evening. Neighboring St. Petersburg announced a 5 p.m. curfew.

With about 3 million people, the Tampa Bay metropolitan area is the second-most populous in the state.

Buckhorn said areas along the Tampa Bay shoreline could expect a dangerous storm surge anywhere from three to eight feet, adding that it would depend on where Irma went.

“What we really fear more than anything is that storm surge,” Buckhorn told CNN’s Anderson Cooper on Sunday.

Jones said the severity of the storm surge depended on which side of the storm Tampa was on.

“If Tampa stays on the east side of the eye, we expect the storm surge to be worse than if the eye moves inland and the west side of the storm hits it,” he said.

That’s because wind from the east side of Irma would be blowing towards Tampa, pushing water from the bay inland and raising the height of the storm surge, he said.

“I will tell you in no uncertain terms — and I am not going to sugarcoat it — this is going to be a difficult storm,” Buckhorn said at the news conference. But he emphasized that Tampa is prepared.

“So look out for your neighbors, take care of each other,” he said. “This is when we are Tampa strong. This is what we do.”