"Heavy rains will begin to affect South Florida and the Keys Friday and continue through Saturday," the Hurricane Center said in an online post. Also predicted is storm surge and flooding, the severity of which depends on the timing of tides.
Florida Gov. Ron DeSantis said the forecast was somewhat unusual in that substantial rains were expected in southwestern Florida on Friday and windy but drier conditions on Saturday. "The rain is actually beating the wind" instead of the two coming together, he said.
"No one's going into emergency posture" yet, DeSantis said, but authorities would monitor for a strengthening storm. "We've got to be ready no matter what."
Some cities and counties across Florida's coastal and low-lying areas, including Pembroke Pines and Miami-Dade County, were offering sandbags to residents to shore up their homes Friday morning.
As a Pacific storm, Hurricane Agatha caused flooding and mudslides that killed at least 11 people and left 20 missing in Mexico, officials said. It caused rivers to overflow their banks and swept away people in homes, while other victims were buried under mud and rocks.
Agatha made history as the strongest hurricane ever recorded to come ashore in May during the eastern Pacific hurricane season since 1949. Climate scientists say tropical systems will become more powerful and destructive because of global warming.