The National Weather Service on Thursday night issued a third fire alert for South Florida this week as a sprawling brush fire in south Miami-Dade County has consumed more than 24,000 acres. Forecasters are once again cautioning residents that more blazes may occur and quickly proliferate.

The newest alert, a fire weather watch, is in effect Friday morning through the evening for Miami-Dade, Broward and Palm Beach counties.

The fire weather watch differs from the two red flag warnings that took effect Monday and Thursday. The watch is a step removed, indicating imminent weather conditions that will fuel fires, while a warning tells residents those conditions are actively occurring.

Regardless, forecasters say winds will be strong (10 to 15 mph with gusts up to 25 mph), humidity will be low (about 20%) and temperatures will be high (mid- to upper 70s). Such factors spell prime conditions for fires to develop and spread rapidly.

These conditions are actively fueling a large brush fire in southeast Miami-Dade in Homestead and near Florida City that has caused traffic mayhem, intermittently shutting down the only routes into the Florida Keys for days.

As of Friday morning, U.S. 1 was open , according to Miami-Dade County Emergency Management, but drivers may experience intermittent closures and delays. Card Sound Road remained closed, according to the Monroe County Sheriff’s Office .

The fires began more than a week ago, then grew and intensified due to dry air and high winds.

On Tuesday, the Florida Forest Service said it was burning around 2,000 acres and was 20% contained. A day later, the agency said it spread to 4,000 acres with about the same percentage of containment.

By Thursday, as the red flag warning was active, Miami-Dade Fire Rescue told the Miami Herald the blaze was burning 24,000 acres of brush — with 30% containment.