"I cannot stress this highly enough: If you are in the projected path of this hurricane, take precautions now," Obama said in an address from Martha's Vineyard.
"The federal government has spent the better part of last week working … to see to it that we're prepared," he added. "All indications point to this being a historic hurricane."
His message and the ongoing mobilization of his administration underscore the lingering lessons from Hurricane Katrina, and an awareness of the impact the monster 2005 storm had on the presidency of George W. Bush.
The Obama administration has pre-deployed federal disaster response teams up and down the East Coast, personally reached out to dozens of state and local leaders, preemptively declared an emergency in North Carolina -- and launched a public relations blitz to let Americans know.
"The federal government is leaning forward, ahead of the storm," Homeland Security Secretary Janet Napolitano told reporters in Washington, D.C., this morning. "The president has directed us to ensure that all needed resources are available and that we should coordinate closely with our local partners."
The news conference followed a slew of press releases detailing the administration's efforts, which included calls from Napolitano to seven governors and five mayors, and the early dispatching of FEMA national assistance teams to states in the storm's path.
"You're seeing FEMA ringing their early alarm bells louder and sooner than they did during Katrina," said presidential historian Douglas Brinkley, author of "The Great Deluge: Hurricane Katrina, New Orleans and the Mississippi Gulf Coast."
"FEMA is painting a worst-case portrait. They're leaving nothing to chance," Brinkley said. "And that's a lesson learned during Katrina."
With Irene just hours from making its first U.S. landfall on the Carolina coast, Obama paused his family vacation to make his first public remarks on the storm before his scheduled return to Washington tomorrow.
From there, he will likely take a leading role behind the scenes as the storm passes overhead, said Mark Merritt, a former FEMA official who is leading the long-term post-Katrina recovery effort in Louisiana.
"He has got to empower his staff, his cabinet secretaries, to do whatever it takes, especially in the preparedness and response phase. But he also needs to be the nation's cheerleader," Merritt said.
"Most importantly, he has to manage expectations," he added. "This is going to be a catastrophic event, and this is going to be a catastrophic event that's going to stretch over hundreds of miles."
Brinkley said Obama will need to quickly play an even bigger role after the storm.
"The lesson from Katrina would be, as soon as the tail winds die down, go to the disaster zone," he said. "People want to see the president of the United States with his heels on the ground, touching flood waters, offering words of reassurance and bringing the American people along with him."