Officials ordered the mandatory evacuation of one coastal Georgia community Wednesday and urged others to do the same as Hurricane Matthew neared Florida and threatened death and destruction up through the Carolinas. Gov. Nathan Deal expanded the state of emergency from 13 to 30 counties.

The National Hurricane Center placed the state’s 100-mile-long coast under a hurricane watch, less severe than a hurricane warning, with winds of 74 mph or greater hitting the state by late Friday. High winds could extend as far inland as Jesup or Statesboro.

The real killer, though, might be the storm surge that, combined with as much as 10 inches of rain, could inundate miles of low-lying tidal areas and cut off barrier islands from the mainland.

Matthew could also be surreptitiously dangerous. Not since 1979 has such a strong storm threatened coastal Georgia. Few residents remember Hurricane David, a Category 2 storm that did modest damage.

Unfamiliarity, though, breeds complacency. State officials worry that many coastal Georgians won’t heed their admonitions to flee Tybee, St. Simons and Cumberland islands or the tidal regions along the coast and, consequently, will be surprised — and endangered — by Matthew.

“We want to make sure that people are preparing for the worst,” said Jason Buelterman, the mayor of flood-prone Tybee Island. “We hope for the best, but we have to be preparing for the possibility that this will be a direct hit.”

By 3 p.m. Wednesday, Buelterman had ordered a mandatory evacuation of Tybee and its 3,000 residents. An additional 27,000 residents in low-lying areas of Chatham County east of Savannah were urged to leave by county commissioners. In Glynn County, 75 miles south, commissioners asked people living on Sea, Jekyll, St. Simons and Little St. Simons islands to evacuate.

Deal, who had declared a state of emergency Tuesday for 13 coastal counties, added 17 southeastern counties to the list Wednesday evening. He also encouraged residents in the six coastal counties to voluntarily evacuate. Earlier in the day, the governor signed an executive order guaranteeing an “uninterrupted supply” of emergency shipments by truckers to southeast Georgia.

School systems along the coast canceled classes Thursday and Friday. Nursing homes, too, were sending patients to higher ground. Emergency officials were on alert.

Matthew threatens to cancel Saturday’s football game in Columbia, S.C., between the Georgia Bulldogs and South Carolina Gamecocks. Hundreds of thousands of coastal South Carolinians have been ordered to evacuate. Classes at USC have been canceled for Thursday and Friday. A USC sports officials said Wednesday that “chances are very, very minimal that this game would be moved outside of Columbia,” though it could be played Sunday or Monday.

In North Carolina, Gov. Pat McCrory declared a state of emergency for more than half the state’s 100 counties, though the storm’s shift further eastward might diminish chances for harm.

Wednesday evening on Tybee Island was relatively calm, with no lines of cars heading west along U.S. 80, which will surely be underwater at times this weekend. Islanders were packing and boarding up as police, fire and TV crews filled the business district about 6 p.m.

Many locals on Tybee and other barrier islands said they’d wait until Thursday to decide to stay or go.

“We boarded up the windows, unlocked the wine cellar and are hunkered down,” said Jane Fraser, who has lived on Sea Island since 1994. “The last time we had a mandatory evacuation it was nothing. If it looked like a direct hit, we would’ve already left.”

Hurricane Floyd prompted a large-scale evacuation in 1999. Georgia, though, hasn’t been hit head-on by a Category 3 hurricane since 1898. The 20th century witnessed a handful of Category 2 or lesser hurricanes, but Georgia’s geographic position — a curved and truncated coastline bowing into shallow water — has kept the big storms at bay.

Matthew could be different. It’s expected to hit Georgia’s southeastern corner, near St. Marys, late Friday or early Saturday. The timing is critical.

If, as expected, the storm is located off the coast, then the counterclockwise winds will pile up water along the beaches and marshes. Add a high tide — one’s scheduled for 2:27 a.m. Saturday off St. Marys — and the surge of water inland could be massive.

Coastal residents got a taste of what’s coming in early September when Tropical Storm Hermine downed trees, caused power outages and dumped 6.4 inches of rain on Alma while notching a 63 mph wind gust near Tybee. Matthew promises worse. But it’s uncertain whether locals learned their lesson.

“We have been very lucky, particularly since the state of Georgia hasn’t had a major hurricane since 1898,” said Clark Alexander, the executive director of the Skidaway Institute of Oceanography near Savannah. “Matthew, though, should be a wake-up call for the public to make sure they have plans in place. This would be a good time to step back and think about your vulnerability.”