It's too soon to know exactly where Hurricane Matthew will be in a few days, or how hard it will hit the United States.
But the storm's latest track shows it making a westward turn toward the US East Coast. And officials in several states in that region say they're not taking any chances.
"If Hurricane Matthew directly impacts Florida, there could be massive destruction which we haven't seen since Hurricane Andrew devastated Miami-Dade County in 1992," Florida Gov. Rick Scott said in a statement. "That is why we cannot delay and must prepare for direct impact now."
Scott declared a state of emergency for his entire state. And North Carolina Gov. Pat McCrory has declared a state of emergency for more than half of the counties in his state.
The potential threat was enough for Rick Knabb, director of the National Hurricane Center, to fire off a warning to Americans.
"U.S. East Coast: find out today if you live in an evacuation zone," Knabb tweeted. "If so, decide where you'd go, how you'd get there if told to go."
Florida residents will likely see tropical storm and hurricane watches later Tuesday morning, forecasters said.
The "extremely dangerous" Category 4 hurricane made landfall in western Haiti Tuesday morning with winds of 145 mph, according to the hurricane center.
CNN forecasters predict the storm could hit parts of Florida starting Thursday night.
CNN's Catherine E. Shoichet contributed to this report.