Saharan dust clouds typically travel across the ocean in late spring and summer. This one was visible during a vibrant sunrise at Midtown Beach in Palm Beach, Florida, on June 27, 2024.

A massive cloud of dust that has traveled thousands of miles from the Sahara Desert is expected to reach Florida as early as the afternoon of June 4 before spreading through the Gulf Coast and Southeast later in the week, forecasters said.

Most of the dust, which is thought to be about 2,000 miles wide from west to east and 750 miles long from north to south, will remain high in the atmosphere and have little effect on air quality and health for most people, according to AccuWeather. Floridians could start to see hazy skies or colorful sunrises and sunsets midweek.

“This is the biggest Saharan dust plume that we've seen so far this year. It is very common to see large plumes of Saharan dust coming across the Atlantic toward the United States in June and July,” AccuWeather Lead Hurricane Expert Alex DaSilva said. “Many people will notice more colorful sunrises and sunsets, and a milky or hazy look in the sky.”

When will the Saharan dust reach states in the US?

The dust cloud has covered the Caribbean islands on its way across the Atlantic toward the United States. In Puerto Rico earlier in the week, the cloud was dense and caused hazy skies, according to the National Weather Service in San Juan. Early in the morning on June 4, the cloud was impacting visibility in Cuba, AccuWeather Senior Meteorologist Adam Douty told USA TODAY.

The plume is expected to reach south Florida by the afternoon or evening of June 4, then push further north to the rest of Florida and parts of Georgia and South Carolina by June 5, according to AccuWeather. By the end of the week, it should reach several other Gulf Coast and Southeastern states including Louisiana, Mississippi and Alabama, AccuWeather reported.

Floridians shouldn't expect to see much of an impact on June 4 because of clouds and some rainfall in the way, Douty said, but they should stay tuned for potentially dazzling sunsets later in the week.

The Saharan dust is expected to linger in the atmosphere over the southeastern United States through the weekend before dissipating, Douty said.

What is the Saharan Air Layer?

The dust is part of a phenomenon known as the Saharan Air Layer, a very dry, dusty mass of air that forms over the Sahara Desert during late spring, summer and early fall, according to the Atlantic Oceanographic and Meteorological Laboratory, part of the National Oceanic and Atmospheric Administration. The dust clouds move over the Atlantic Ocean every few days and can reach as far west as Texas.

This isn't the last time the United States will see Saharan dust this summer, Douty predicted. The round of dust headed our way in the first week of June isn't all that strange, as we usually see one or two events this large each year, but it is a little earlier than usual, he said.

Saharan dust can have a big impact on storms in the United States, even suppressing hurricanes because of the warmth, dryness and strong winds (25-55 mph) associated with the Saharan Air Layer, the lab said. It can also suppress clouds and thunderstorms. Air in a Saharan Air Layer is about 50% less moist than a typical tropical atmosphere, causing weaker cyclones.

"Some areas will experience their hottest days of the summer when the SAL’s dry, dusty air is overhead and afternoon thunderstorms are being stifled," the lab's website reads.

One of the most noticeable impacts is the vibrant sunsets and sunrises visible during a Saharan dust outbreak. A heavy amount of dust in the atmosphere enhances and prolongs the yellow and red hues we see as the sun's light passes through the atmosphere.

Dust could collide with Canadian wildfire smoke

The Saharan dust could end up colliding with smoke infiltrating the United States from wildfires burning in Canada Douty said.

The wildfire smoke has caused unhealthy air quality in several states in recent days, including parts of Minnesota and Wisconsin, and moderate air quality across much of the eastern half of the country. While the smoke is causing unhealthy air quality in states bordering Canada, most of it remains in the upper levels of the atmosphere and is not causing serious air quality issues in the rest of the country.

Douty said there may be a small zone where the smoke and dust interact over the Southeast later in the week, but it shouldn't affect health or safety, except for sensitive groups.

This article originally appeared on USA TODAY: Massive cloud of dust from the Saharan Desert is headed for Florida

Reporting by Jeanine Santucci, USA TODAY / USA TODAY

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