The new storm, Tropical Storm Milton, will intensify to a Hurricane before it reaches Florida this week.
Milton will intensify to a tropical storm on Monday and make landfall on the Florida Peninsula by Wednesday.
The storm could land as a Category 3- or higher-class hurricane.
The National Hurricane Center urges residents on the west coast to Florida to prepare a hurricane plan and stay informed as the forecast changes.
Milton will increase the flooding threat by a significant amount when it reaches Florida. A separate system has already saturated Florida this weekend with rains of 2 to 5 inches.
By the time Milton leaves Florida, the five-day rainfall total could be 10 inches or higher.
The west coast of Florida is also susceptible to storm surges and wind damage.