Miami-Dade Mayor Carlos Gimenez issued an evacuation order for residents living in mobile parks and low-lying areas prone to flooding Saturday afternoon.
He said three shelters will open in Miami-Dade County at Dr. Michael M. Krop Senior High School, Booker T. Washington School and Robert Morgan Senior High School. Dr. Michael M Krop will be the only shelter that is pet friendly.
Tropical storm force winds from Isaac could begin in South Florida as early as Sunday morning.
Late Saturday, FPL officials reported that a main feeder power line was down in Key Biscayne, leaving about 2,000 people in the area without power. Crews were on scene working on the line.
Gimenez urged residents to begin putting up their shutters, gathering supplies and filling up their cars with gas.
"You should begin putting up your shutters now. Even tropical storm winds can cause damage so you shouldn’t wait until the last moment to protect your home," he said.
Miami International Airport will remain open but six flights had been cancelled on Saturday. The Fort Lauderdale-Hollywood International Airport was also to remain open, but 120 flights were cancelled in total from Friday to Sunday. Click here for status of flights there.
Meanwhile, public schools in Miami-Dade and Broward County were canceled Monday. All Miami-Dade Courts and Clerk of Courts' offices and the federal courthoues in Miami and Broward will also be closed Monday.
Miami-Dade Transit personnel, Metrobus, Metrorail and Metromover would be suspending operations at noon on Sunday until further notice.
"Things have changed in the last less than 24 hours, we thought we were going to be in a much better situation, things have shifted to the right and to the east, and we may have a hurricane instead of just a tropical storm," Gimenez said.
He said residents should have food and water for three days, secure outside furniture and stay alert to the latest storm developments.
Broward County will also open homeless shelters and buses were picking up people at designated locations. They are the Broward Outreach Center at 2056 Scott Street in Hollywood, Pompano Beach City Hall on Atlantic Boulevard and First Avenue and at the Salvation Army Lodge at 1445 West Broward Boulevard in Fort Lauderdale.
The Broward County American Red Cross is also opening two general population shelters for residents of low-lying areas and areas prone to flooding, mobile home residents and those who feel their structure is unsafe. The shelters are opening at 7 p.m. Saturday at Rock Island Elementary at 1701 Northwest 23rd Avenue in Fort Lauderdale and Millennium Middle School at 5801 Northwest 94th Avenue in Tamarac.
Millennium Middle School is a pet friendly shelter.
The National Weather Service and the National Hurricane Center meanwhile, are busy forecasting Isaac and encouraging South Florida residents to take preparations ahead of the storm.
Dade and Broward could have several inches of rain and tropical storm force winds, while the Keys could experience hurricane force winds, they said.
"Today is really the day when we need to start doing our preparations because by tomorrow, especially for mainland South Florida, at least by late tomorrow morning, we could already be starting to experience the first tropical storm winds," Robert Molleda of the National Weather Service told NBC 6. "And then as the day goes on Sunday, those winds will be become more steady and then by night, those winds will probably be at their highest point."
The agencies also say to keep in mind that the forecast track could still change slightly depending on land interaction with Cuba, so they urge residents to not let their guard down.
"It's a pretty large storm," Molleda said. "That tropical force wind field, even if the center passes over the lower Keys, Miami-Dade and Broward County will likely see some tropical force storm winds, probably for most of the day on Sunday."
As of 11 p.m., Isaac was located about 65 miles northeast of Camaguey, Cuba and 340 miles east-southeast of Key West. The center of Isaac was moving along the northern coast of eastern Cuba with little change in strength. Isaac had maximum sustained winds at 60 mph and was moving northwest at 17 mph.
Miami Children's Hospital's urgent acre centers will be closed Sunday, and children requiring care can visit the Miami Children's Hospital emergency department at 3100 SW 62nd Avenue.
Zoo Miami was closed Saturday due to bad weather brought by Isaac. Jungle Island is closing Saturday at noon and all day Sunday. Miami Seaquarium will be closed at 2 p.m. Saturday and all day Sunday.
Meanwhile, resident Jessie Roman said he wasn't really worried about the storm.
"High winds maybe small power outage...boil water I don't think it will be a big deal," he said.