(CNN) — Coastal Louisiana could experience tropical storm force winds from Hurricane Gustav as early as Sunday night, Louisiana Gov. Bobby Jindal said, as he made a last appeal for residents to evacuate.

“Don’t just look at landfall. Look at those tropical storm force winds,” he said. “That’s when it will not be safe to be driving or be on the road.”

Tropical storm winds range from 39 mph to 73 mph, according to the National Hurricane Center.

Hurricane Gustav, with sustained winds of maximum winds of 115 mph with higher gusts, is currently a Category 3 hurricane, the NHC said. Its hurricane force winds extend outward up to 50 miles, while its tropical force winds extend up to 200 miles.

“There is still time for our people to evacuate,” Jindal said. “We need to take this storm very seriously. Whether it’s a strong Category 3 or border-line Category 4, you’re going to see strong tidal surge, strong wind speeds. The National Hurricane Center doesn’t know precisely where the storm will strike Louisiana’s coast,” he said.

“The important thing though is for people to take these warnings, take this opportunity very seriously. Now is the time to get out of harm’s way.”

Maps of Gustav’s path shows that it could strike southern Louisiana and other areas battered by Hurricane Katrina in 2005.

All but three of Louisiana’s 64 parishes had declared an emergency, and Jindal said nearly every parish along the coast had issued a mandatory evacuation.

“I strongly encourage people to heed those evacuations and warnings,” he said.

Jindal said officials were working to evacuate hospitals and nursing homes. “I strongly, strongly encourage those nursing homes that are non-mandatory evacuation parishes to also evacuate,” he said.

Earlier Homeland Security Secretary Michael Chertoff said a number of Louisiana hospitals that had planned to ride out the storm were now moving critical-needs patients.

Because of that change, “we’ve had to increase tempo of our air flights,” he said.