Big Cypress wildfire shuts down Alligator Alley, becomes Florida’s largest blaze on record

The smoke rolled in so thick that troopers said they could barely see the hoods of their own cruisers.

Shortly after 9 p.m. on Feb. 25, Florida Highway Patrol officers shut down a 57-mile stretch of Interstate 75 — the Alligator Alley corridor that links Naples to the Fort Lauderdale area — as a wall of smoke from a wildfire in Big Cypress National Preserve dropped visibility to almost nothing. Traffic was diverted onto two-lane roads. Truckers idled at gas stations on either side of the Everglades. Drivers posted dash-cam video of the interstate vanishing into gray.

The fire was not in a pine forest out West but in a swamp in South Florida. By the time crews declared the blaze 100% contained on March 17, the National Fire, as it was named, had charred 35,027 acres of Big Cypress, becoming the largest single wildfire recorded in modern Florida history.

Officials say the blaze was human-caused and burned for 23 days in one of the state’s most protected wetlands, forcing highway closures, rural evacuations and weeks of unhealthy air over parts of the peninsula. The fire unfolded against the backdrop of one of Florida’s worst droughts in decades and is already being cited by land managers and climate scientists as a warning about how and where wildfires can now erupt.

“Public and firefighter safety remain the highest priorities on this incident,” the National Park Service said in one of several daily updates as the fire spread south of I-75. The agency, which manages Big Cypress, said a combination of deep drought and a hard freeze earlier in February left “an unusually heavy and highly receptive fuel bed” in the preserve’s prairies and cypress stands.

A human spark in a dry winter

The National Fire was discovered late on Feb. 22 on federal land near mile marker 80, south of I-75 and east of State Road 29 in Collier County. It was initially known informally as the Mile Marker 80 Fire before mapping confirmed it lay within the boundaries of Big Cypress National Preserve.

Within 24 hours, park fire managers reported that the blaze had grown to about 5,000 acres with zero containment, driven by steady winds and parched vegetation. By Feb. 24, it had tripled in size to roughly 15,000 acres. On Feb. 25, the estimate jumped again to more than 24,000 acres.

Investigators have determined the fire started from human activity, not lightning, though the specific cause — such as an escaped debris burn or equipment malfunction — has not yet been made public. The National Park Service and state officials say the inquiry is ongoing.

The timing was especially bad. By mid-February, nearly all of Florida was in some degree of drought, with much of the peninsula classified in severe or worse conditions. A strong cold snap earlier in the month killed off grass and brush across South Florida. As that vegetation dried, it created abundant fuel in an ecosystem visitors typically associate with standing water.

On top of that, fire-weather indices were unusually high for the region. In the days around ignition, relative humidity dipped to around 30%, and winds in the 15- to 25-mph range fanned the flames through sawgrass prairies, pine islands and cypress strands south of the interstate.

Shutting down Alligator Alley

For motorists, the most dramatic moment came three days into the blaze.

Through Feb. 24 and 25, the Park Service and state transportation officials warned that smoke was drifting across I-75, U.S. 41 and State Road 29 and could cut visibility without warning, especially at night and around dawn. Late on Feb. 25, a wind shift pushed a dense band of smoke over Alligator Alley just as temperatures dropped and the air settled over the swamp.

As visibility deteriorated, Florida Highway Patrol closed the interstate between exit 23 near toll plazas east of Naples and exit 80 near State Road 29. The closure lasted until about 6 a.m. the next morning.

Troopers urged drivers to use alternate routes such as U.S. 27 around the northern edge of the Everglades, adding hours to freight hauls and commuter trips. For a corridor that carries a heavy share of South Florida’s east-west truck traffic and tourism, an overnight outage on that scale is extremely rare.

Officials kept intermittent lane closures and warnings in place for days afterward as smoke continued to drift across interstate lanes and nearby highways.

Fire at the edge of small communities

While no homes were destroyed, the fire crept close enough to several small communities to trigger evacuations and intense concern.

Residents of Jerome, an unincorporated community south of I-75 and west of State Road 29, were first told to be ready to leave as the fire expanded. As crews prepared for large defensive burn operations along the southern flank on Feb. 28, local emergency managers ordered Jerome evacuated to keep people out of the path of planned ignitions and potential spot fires. Officials also advised residents of Copeland, another small community in the area, to be prepared to go if conditions worsened.

Collier County Emergency Management coordinated roadblocks and shelter options as crews worked along State Road 29 and interior preserve roads. The Park Service temporarily closed all lands south of I-75, east of State Road 29, north of U.S. 41 and west of key interior routes, citing active fire, smoke and the need to keep the public clear of aircraft and heavy equipment.

Throughout, officials stressed that the main threat to residents came from smoke and limited evacuation routes, not burning homes. “There is currently no immediate threat to residential structures,” the Park Service said in a Feb. 23 statement, even as it warned that conditions could change quickly.

A complex, multi-agency fight

The initial response to the National Fire was led by the National Park Service’s South Florida Fire and Aviation program and local Big Cypress crews. As the fire crossed 20,000 acres and complicated operations piled up along highways and private inholdings, the agency requested a Type 2 incident management team, a designation for large, complex wildfires.

On Feb. 26, command transferred to the Southern Area Gray Incident Management Team, which continued to operate under the Park Service as the host agency. State and local partners included the Florida Forest Service, Collier County Sheriff’s Office, Collier County Emergency Management, the Greater Naples Fire Rescue District, Florida Highway Patrol and the Florida Department of Transportation.

Crews used a combination of bulldozed lines where feasible, natural barriers such as sloughs and canals, and strategic firing — deliberately igniting vegetation ahead of the main fire front to deprive it of fuel. Helicopters conducted aerial ignition in remote interior pockets, dropping small incendiary spheres to burn out unburned islands within the fire perimeter in a controlled way.

Managers described a containment “box” bounded in part by I-75 to the north, State Road 29 to the west, Turner River Road and wagon wheel trails to the east and interior preserve lines to the south. The goal was to keep the fire within that box, protecting communities and infrastructure while allowing some fire to play its natural ecological role in certain habitats.

By March 3, the fire’s footprint had reached just over 35,000 acres, where it would ultimately be mapped. Containment rose steadily as burnout operations succeeded and weather moderated. On March 7, officials reported 67% containment. Over the next 10 days, crews focused on mopping up hot spots, particularly in areas of peat and heavy organic soil that can smolder for days.

When officials declared the fire fully contained on March 17, suppression costs had already surpassed $4.5 million, not counting local overtime, lost business and health impacts.

A fire that challenges assumptions

Wildfire is not new to Florida. The state’s natural pinelands and prairies evolved with frequent, low-to-moderate intensity burns, and both state and federal agencies use prescribed fire as a cornerstone of land management. Big Cypress, a 729,000-acre preserve established in 1974, regularly conducts planned burns to reduce fuel and maintain habitat for species such as the Florida panther and wading birds.

What stands out about the National Fire is its size, its human origin and its setting.

According to state and federal fire data, no single wildfire in modern Florida records has burned more acreage than the 35,027 acres scorched in Big Cypress this year. Many of the state’s worst fire years, such as 1998, involved hundreds of smaller lightning-sparked fires that collectively burned more land and destroyed more structures, but no one blaze matched the footprint of the National Fire.

Ecologists say a fire of this scale in drought-stressed wetlands raises specific concerns. In addition to scorching grasses, shrubs and some trees, high-intensity burning in cypress swamps can consume peat and organic soil, lowering ground levels. Over time, that can alter how water flows through the Everglades system — a crucial issue for both ecosystem health and South Florida’s water supply.

There are also questions about what regrows. Invasive plants such as Brazilian peppertree and Old World climbing fern are known to colonize disturbed ground quickly. If they gain a foothold in burned areas, they can outcompete native vegetation and change fire behavior in future seasons.

Looking ahead

State wildfire records show that the National Fire is part of a broader 2026 pattern, with multiple fires exceeding 1,000 acres reported across central and South Florida during the winter dry season. Many of those, like the Big Cypress blaze, have been linked to human causes rather than lightning.

Land managers and climate researchers say the combination of more people living and working near wildlands, more opportunities for ignition and more frequent or intense droughts is shifting Florida’s fire risk.

The Park Service has framed the National Fire as a case study in both the dangers and the necessity of fire. “Fire is a natural part of many of the ecosystems in Big Cypress,” the preserve notes in its public materials, adding that prescribed burning and managed natural fires play an important role in maintaining biodiversity. At the same time, the agency has emphasized that accidental ignitions during extreme conditions can quickly overwhelm suppression resources and threaten lives and infrastructure.

For drivers on Alligator Alley and residents of Jerome and Copeland, the distinctions between “natural” and “unnatural” fire matter less than whether they can safely get home or breathe the air outside. For now, the blackened tree trunks and patches of green regrowth in Big Cypress are a visible reminder that even swamps can burn when conditions line up — and that a single spark, in the wrong week of a dry winter, can shut down a highway and rewrite the record books.