Florida Flooded Twice in One Week. The Reason Is Under Your Feet.

On the last Tuesday of October, with the sun out and no storm on the map, the ocean came over the seawalls along Collins Avenue in Miami Beach. Gauges in Miami and Fort Lauderdale hit about two and a half feet above normal high tide, major flood stage. Fort Lauderdale closed roads, and Miami logged more than 11 straight days of coastal flooding. A University of Miami researcher called it the highest King Tide on record.

Five days later it was the sky's turn. A slow moving storm parked over the Space Coast on November 1 and would not leave. By Monday morning the Weather Service had declared a flash flood emergency for Palm Bay, its most urgent flood warning, with more than 20 inches of rain on the ground.

Residents paddled kayaks down their own streets, more than 60 people were rescued, and the governor declared a state of emergency. Mayor Rob Medina said the storm "devastated our community."

Two floods, two causes, one week. One came from the ocean, the other from the sky. What connects them is something few people think about when they picture Florida: it is astonishingly flat.

Flood one: the ocean comes in

King Tides are the highest tides of the year, and they arrive every fall. This October's was pushed even higher by days of strong onshore wind.

On flat land, a few extra feet of water travels a long way. In Marathon, in the middle of the Keys, a tide just one foot above normal reaches about a quarter of the town. At three feet, more than half of it is under water. That is the same kind of water a hurricane's storm surge brings, only bigger.

Flood two: the rain has nowhere to go

Look at the bottom of that chart. By the ocean's measure, Palm Bay is one of the safest towns in Florida. Only about 0.2 percent of the city sits low enough for even a three foot tide to reach, and the typical spot is about 22 feet up.

It flooded anyway, because flat land is also bad at getting rid of rain. On hilly ground, water runs downhill and away. On flat ground, it mostly sits until ditches, canals and creeks can carry it off. Much of Palm Bay was built on drained wetlands, and a lot of its water has to work its way out through Turkey Creek to the Indian River Lagoon. Two feet of rain in two days was far more than it could move.

It was not the first time. In November 2023, Palm Bay took about 11 inches in a single day and broke its November rainfall record.

Why Florida floods so easily

Ask Americans to name the flattest state and most will say Kansas. The average elevation in Kansas is about 2,000 feet. In Florida it is about 100. The state's highest point, Britton Hill in the Panhandle, stands 345 feet, shorter than a football field is long. Plenty of Miami condo towers are taller.

The only countries flatter on average are tiny island nations like the Maldives and city states like Singapore. The Netherlands is roughly as flat as Florida, and a quarter its size.

The reason lies underground. For millions of years, Florida sat beneath a warm, shallow sea, where shells, coral and sediment hardened into the limestone that now sits under 23 million people. That rock is full of holes, like a hard sponge. It holds the Floridan Aquifer, the source of most of the state's drinking water, and it lets seawater seep up from below, which is why Miami cannot simply wall itself off from the sea.

It keeps happening

A town can be safe from one kind of flood and exposed to the other. In recent years, Florida's major floods have split almost evenly between the two. To see how your town ranks on both maps, check our flood risk rankings for 50 beach towns.

Flat doesn't have to mean flooded

America has been here before. About half of New Orleans sits below sea level, and after its levees failed during Hurricane Katrina in 2005, the country spent about $14.5 billion on stronger levees, floodwalls and pumps. The Dutch rebuilt after a 1953 North Sea flood killed more than 1,800 people, and later began giving rivers room to spill onto land set aside for it.

Flat places can be safe places when water is planned for. Some Florida towns are raising roads, adding pumps and fitting storm drains with valves that stop the tide from pushing back up. For anyone choosing where to live, it is worth asking which towns are doing that work.

The moves keep coming: about 875 new residents a day, and the biggest group arriving from other states is in their 50s and 60s. Flatness is no reason to skip Florida. It is a reason to choose the town, and the street, with care.

In a state whose highest point is shorter than a football field, the few feet under your house matter more than you think.