Hurricane Idalia strengthened to a Category 4 storm early Wednesday as it barreled towards Florida, threatening “catastrophic” impacts, with officials forecasting it will slam into the coast within hours. Authorities in the southern US state described Idalia and its potentially deadly storm surge as a once-in-a-lifetime event for Florida’s northwest coast, as they ordered mass evacuations and issued flood alerts ahead of a projected landfall Wednesday morning. The US National Hurricane Center (NHC) said Idalia, which earlier raked western Cuba, had strengthened to a Category 4 storm as of 5:00 am EST (0900 GMT), with maximum sustained winds of 130 miles (215 kilometers) per hour. “Idalia is a category 4 hurricane… Idalia could continue to strengthen before it reaches the Big Bend coast of Florida in a few hours,” the NHC said in an advisory. “While Idalia should weaken after landfall, it is likely to still be a hurricane while moving across southern Georgia, and near the coast of Georgia or southern South Carolina late today.” Warm waters in the Gulf of Mexico are expected to further turbocharge Idalia, with wind speeds topping 150 mph, the NHC said. It warned of a potentially disastrous storm surge inundation of 12 to 16 feet (3.5-5 meters) in some coastal areas. “Very few people can survive being in the path of a major storm surge, and this storm will be deadly if we don’t get out of harm’s way and take it seriously,” said Federal Emergency Management Agency (FEMA) chief Deanne Criswell. In the small coastal town of Steinhatchee, resident Robert Bryant was making final preparations Tuesday to evacuate inland with his two cats and a dog. “We are out on the water, so we are going to be the worst ones to get hit,” said the 18-year-old student, whose home built on stilts is close to the mouth of a river. “Hopefully, it just blows over and we have a bit of wind… but you prepare for the worst and hope for the best,” he told AFP. Another Steinhatchee resident, 71-year-old John Paul Nohelj, told AFP he would stay put. “If you live near the water, you’re gonna get a wet butt once in a while,” he said, downplaying the risk. The nearby cities of Tampa and St. Petersburg, part of a metropolitan area that is home to more than three million people, are of particular concern, authorities said. “There’s a danger of life-threatening storm surge along portions of the Florida Gulf Coast from Tampa Bay to the Big Bend region,” said Matthew Payne of FEMA’s Office of Response and Recovery. Idalia was already battering parts of Florida, with flooding seen in Fort Myers Beach south of Tampa. The emergency management department of Pinellas County, on Florida’s west central coast, reported some flooded roadways early Wednesday, with winds of up to 60 miles per hour and traffic signals out. “All residents are advised to stay off the roads and remain sheltered,” the department posted on social media. Governor Ron DeSantis urged those in the evacuation areas in 23 counties along Florida’s Gulf coast to go “now,” and head to shelters or hotels outside the danger zones. The US presidential candidate said the hurricane appeared to be the strongest to impact the region in more than a century. Meteorologists are also pointing to a rare blue supermoon which could further raise tides above normal levels just as Idalia pounds the coastline. Almost 150 people were killed last year when Hurricane Ian slammed Florida’s west coast as a Category 4 storm, bringing ocean surges and strong winds that downed bridges and swept away buildings. Idalia is expected to make landfall further north in the so-called Big Bend area — a vast marshy region which, unlike most other coastal areas around Florida, does not have barrier islands. The storm is forecast to dump up to 12 inches (30 centimeters) of rain in parts of Florida, Georgia and South Carolina, potentially triggering flash and urban flooding, and tornadoes were also possible in parts of Florida, Georgia and the coastal Carolinas on Wednesday, according to the NHC. Tampa International Airport closed ahead of Idalia’s arrival, while flights were disrupted along the US east coast as another hurricane, Franklin, churns in the Atlantic. The ports of Jacksonville, Fernandina and Canaveral were closed to vessel traffic as of Tuesday night due to the forecast strong winds, according to the US Coast Guard. Georgia, North Carolina and South Carolina are also under storm watches as Idalia is expected to cross northeast over Florida before exiting into the Atlantic. All four states could see flooding Wednesday and Thursday, the NHC said. In Cuba, the storm flooded several communities including parts of the capital Havana and knocked out power to about 200,000 people but there were no deaths reported. The storm then moved out over the Gulf, which scientists say is experiencing a “marine heat wave” — energizing Idalia’s winds as it raced towards Florida. Scientists have warned that storms are becoming more powerful as the world warms due to climate change.