A cloud of Saharan dust over the Caribbean on Wednesday is expected to drift into South Florida as early as Wednesday night, spreading across the state on Thursday and bringing drier weather after several days of rain.

The dry air and dust, known as the Saharan Air Layer, have traveled more than 5,000 miles from North Africa as a discernible mass that even someone without a degree in meteorology could identify on satellite. The plume is expected to fall apart in coming days, with some dust moving into the southeast Atlantic Ocean, potentially grazing Georgia and South Carolina, and some scattering across the Gulf, likely filtering into as far as Texas by Friday and into the weekend.

“It’s just south of the tip of Florida right now, over the Bahamas,” George Rizzuto, a meteorologist with the National Weather Service office in Miami, said Wednesday morning. “We’ll see that ramp up over South Florida in the next 18 to 24 hours.”

When the plume arrives in Florida, Mr. Rizzuto said, it will dry out the atmosphere and prevent storms from developing. This drier weather will come after three days of heavy rain in Florida.

The dust is lifted off the Sahara by winds.

The Saharan Air Layer forms when winds lift sand and minerals from the Sahara in North Africa into the atmosphere. It then gets whisked away by a strong wind current, which sometimes pushes it north into Europe, but more commonly carries it west across the Atlantic Ocean. It usually reaches the Caribbean and the Gulf Coast region several times a year.

The dust events occur year-round but are most common from about mid-May into August, usually peaking mid-June to July.