of emergency a day earlier, was drenched by heavy rains and strong winds from the storm.
The declarations make funds available to respond to the storm and order government agencies to implement emergency preparedness plans.
A hurricane warning was in effect east of Morgan City Louisiana to Destin, Florida, including metropolitan New Orleans, which is marking the seventh anniversary of Hurricane Katrina, which devastated the city and killed around 1,800 people.
The storm is forecast to hit as a category two hurricane on the five-point Saffir-Simpson scale -- with top winds swirling at 96-110 miles (83-95 kilometers) per hour -- when it makes landfall.
"We are encouraging everyone to get prepared now to ensure that you have an evacuation plan in place, plenty of water, non-perishable food items, hygiene supplies, sufficient clothing and any prescription medications you or your family may need in the event of the storm," Louisiana Governor Bobby Jindal said in a statement.
"As with every storm, we always hope for the best and prepare for the worst."
He recommended voluntary evacuations within the hurricane watch area, which includes low-lying areas, those zones outside of levee protection and areas south of the Intracoastal Waterway.
Alabama Governor Robert Bentley said he was mobilizing the resources that his community needed as the storm approached.
"I am urging everyone to take precautions now, monitor weather warnings and be prepared for whatever Isaac may bring," he said.
Bentley ordered mandatory evacuations in parts of Mobile and Baldwin Counties.
Alabama Emergency Management Agency Director Art Faulkner urged residents to "make preparations now for the potential impact of strong winds and heavy rains."
The National Hurricane Center has also issued both a tropical storm warning and a hurricane warning for multiple counties in Mississippi.
Mississippi Governor Phil Bryant authorized the state's National Guard to deploy 10 members of its civil support team to coastal counties, and urged residents to finalize their preparations.
"We are taking the threat of impact from Isaac seriously, and we are working to ensure that Mississippi is well-prepared," Bryant said.
"Sound preparations will enable us to ramp up our response without losing time if the situation worsens."