(CNN) Hurricane Irma strengthened to a Category 4 storm Monday, churning west in the Atlantic Ocean and prompting emergency declarations in Florida and Puerto Rico. Although Irma's path remains uncertain, the possibility it could threaten the United States led Florida Gov. Rick Scott to declare a state of emergency in all 67 counties in his state. "In Florida, we always prepare for the worst and hope for the best, and while the exact path of Irma is not absolutely known at this time, we cannot afford to not be prepared," Scott said in a statement released late Monday afternoon. "This state of emergency allows our emergency management officials to act swiftly in the best interest of Floridians without the burden of bureaucracy or red tape."