With just hours to go before Hurricane Michael makes landfall, the monster system strengthened to a Category 4 storm, packing dangerous winds of 145 mph.
The storm, which rapidly gained force overnight, is just 90 miles off the coast of Panama City, Florida.
The National Weather Service's Tallahassee office warned that Michael is an "unprecedented" storm, as there are no records of a Category 4 hurricane making landfall in the Florida Panhandle area.
"If you live along the coast and were told to evacuate...this is YOUR LAST CHANCE," the office wrote on Twitter. "Hurricane Michael is an unprecedented event and cannot be compared to any of our previous events. Do not risk your life, leave NOW if you were told to do so."
Among the hazards the storm is bringing are life-threatening storm surge of up to 14 feet in some areas. Some places will also see a foot of rainfall, which could produce disastrous flash flooding.
After Michael comes ashore sometime in the early afternoon Wednesday, it will move upward toward Georgia and the Carolinas, which were already devastated by Hurricane Florence last month.
Photos posted online have showed some areas were already experiencing flooding.
LOOK AT THIS! These were taken by a viewer who lives on the Bay near Sandestin. The water has risen already up to the sea wall. There is still more to come for storm surge. DO NOT WAIT, EVACUATE. @WMBBTV @OCSOALERTS @SouthWalton @SWFDINFO @WCSOFL #HuricaneMichael pic.twitter.com/VOzvaysQZa— Peyton LoCicero (@PeytonLocicero) October 10, 2018