When water temperatures drop below 68°F (20°C) in the fall, Florida manatees migrate to warm-water refuges scattered across peninsular Florida. These include natural freshwater springs, power plant discharge zones, and warm-water canals in the southern part of the state. The migration typically begins in November and lasts through March, with manatees returning to their wider coastal range once spring temperatures rise.
Why Cold Water Is Dangerous for Manatees
Manatees have an unusually low metabolic rate for their size, which means they can’t generate enough body heat to survive prolonged exposure to cool water. Once water temperatures fall below 68°F, their bodies begin to lose heat faster than they can replace it. Extended exposure triggers a condition called cold stress syndrome, which can cause skin lesions, immune system failure, intestinal problems, and death.
Cold stress remains a real and recurring threat. In January 2025, which was significantly colder than normal across most of Florida, cold stress was the diagnosed cause of death in 33 out of 213 necropsied manatee carcasses with a known cause of death. The risk climbs not just with how cold the water gets, but with how many consecutive days manatees are exposed to it.
Natural Springs: The Original Winter Refuges
Florida’s freshwater springs are the manatees’ oldest and most reliable winter destinations. These springs discharge water at a constant 72°F year-round, well above the danger threshold. Blue Spring State Park, along the St. Johns River in central Florida, is one of the largest winter gathering sites in the state. Visitors there can see hundreds of manatees packed into the spring run during peak cold months.
Crystal River and Homosassa Springs on the Gulf Coast side are other well-known natural refuges. Historically, these springs defined the northern boundary of the manatee’s winter range. Before power plants existed, researchers estimated that Sebastian Inlet on the Atlantic Coast and Charlotte Harbor on the Gulf Coast marked roughly how far north manatees could survive the winter. South of those lines, manatees had enough natural warm water to get through the season.
Power Plants as Artificial Warm-Water Sites
Starting in the mid-1900s, coal and gas-fired power plants along Florida’s coast began discharging warm water used in their cooling systems. Manatees quickly discovered these outflows and began congregating around them each winter. Plants like Tampa Electric’s Big Bend facility and the FPL Fort Myers plant became major gathering points, essentially expanding the manatee’s viable winter range northward beyond what natural springs alone could support.
This relationship helped manatee populations recover over several decades, but it created a dependency with serious long-term risks. As older power plants are decommissioned, upgraded, or switched to renewable energy, their warm-water discharges disappear. The Marine Mammal Commission has warned that losing these artificial refuges will increase the risk of cold stress deaths. When one warm-water discharge on Amelia Island in northeast Florida was relocated to deeper water to meet water quality standards, it effectively eliminated the site as a manatee refuge overnight.
Restoring natural springs and improving water quality are considered the best long-term alternatives, but both are expensive and will take years to implement.
Summer Range vs. Winter Range
The contrast between where manatees spend summer and winter is striking. During warm months, manatees roam widely. Their range can extend west to Texas and north as far as Delaware Bay, sometimes even beyond. They follow coastlines, entering rivers, estuaries, and bays to feed on seagrass and other vegetation.
As fall arrives and water cools, that range contracts dramatically. Manatees funnel back into peninsular Florida, concentrating at known warm-water sites. The southern third of the Florida peninsula, including Broward, Miami-Dade, and Monroe Counties, stays warm enough that manatees there face relatively little cold stress risk. That region accounted for just 3.4% of all confirmed cold stress deaths in one long-term study. The real danger zone is central and northern Florida, where winter temperatures fluctuate and manatees depend on specific refuges to survive cold snaps.
How They Spend the Winter Months
Manatees don’t simply park at a warm spring and stay put for five months. They make regular foraging trips away from their refuges, sometimes traveling considerable distances to reach seagrass beds or other food sources, then returning to warm water when they need to reheat. Researchers tracking manatee movements in winter have recorded many sightings at unnamed sites away from known refuges, most of which involve animals on these feeding excursions.
At the refuges themselves, manatees crowd together in large groups. Blue Spring can host hundreds of animals in a relatively small spring run. This concentration is driven by necessity rather than social preference. The warm water plumes from springs and power plants cover limited areas, so manatees have no choice but to share tight quarters.
Winter Protection Rules
Federal regulations establish specific protections around manatee wintering sites. From November 15 through March 31 each year, all waterborne activities, including swimming, diving, and boat traffic, are prohibited in designated manatee sanctuaries. In other protected areas like Tampa Electric’s Big Bend Manatee Refuge and the Port Sutton Manatee Refuge, watercraft must operate at idle speed during the same period.
Kings Bay in Crystal River has particularly detailed restrictions. When the winter rules are in effect, all waterborne activities are banned within specified distances from existing manatee sanctuaries in the area. November is designated Manatee Awareness Month in Florida, partly because it coincides with the start of the seasonal migration and the increased risk of boat strikes as manatees move through busy waterways to reach their winter destinations.