Roads flooded in coastal Louisiana and Mississippi, and thousands were without power even before the the storm made landfall.
Bertha's maximum sustained winds were near 50 mph as it came ashore but it was expected to weaken to a tropical depression after moving inland.
Arthur formed Saturday in waters off Florida, marking the sixth straight year that a named storm has developed before June 1.
Tropical Storm Dorian is bearing down on Puerto Rico, which is still recovering from 2017's Hurricane Maria.
The slow-moving storm could bring up to 25 inches of rain to some parts of the South, and it may become a hurricane as early as Friday.
Tropical Storm Michael could strengthen into a hurricane by Tuesday night or Wednesday, the hurricane center said.
Tropical Storm Chris is forecast to become a hurricane by Monday while Beryl advances upon the Caribbean.
Florida, Alabama and Mississippi declared states of emergency on Saturday.
While Miami returns to normalcy after Irma, the neighborhood of Little Havana is still without power.
While much of the population in Miami evacuated, some residents waited it out from their high-rises.