It's one of the most significant Saharan dust events in decades, forecasters said.

A huge plume of dust and sand, blown by the wind from the Sahara Desert, has finally reached the U.S. mainland.

It's one of the most significant Saharan dust events in decades, forecasters said.

The densest plume of dust began to emerge off western Africa last weekend and has now moved into the Gulf of Mexico and the South, the Weather Channel said.

The mass of extremely dry and dusty air known as the Saharan Air Layer forms over the Sahara Desert and moves across the North Atlantic every three to five days from late spring to early fall, peaking in late June to mid-August, according to the National Oceanic and Atmospheric Administration.

It can occupy a roughly 2-mile thick layer in the atmosphere, the agency said.

"The main impacts of the Saharan dust are a whitening of the sky during daylight hours, redder sunsets, and decreased air quality," the National Weather Service said.

Here are a few images from social media of the dust as it settled over the southern U.S.:

The #dust has arrived over #Atlanta, as while there are also high clouds, the sky is noticeably milkier today #gawx pic.twitter.com/7PkfmBUObQ

— Stu Ostro (@StuOstro) June 26, 2020

@WFLAamanda #SaharanDust Pine Island Florida at Sunset last evening. pic.twitter.com/wgG56j50DW

— Mike Gallagher (@mikegallagher24) June 26, 2020

Brown Haze can be seen in the Sky over Corpus Christi this morning indicating the Saharan Dust has arrived. #stxwx pic.twitter.com/aigikxVeQJ

— NWS Corpus Christi (@NWSCorpus) June 26, 2020

Sahara dust rolling into Panama City Beach @spann pic.twitter.com/2OGDtGIFmi

— Nicole Penny (@npenny2012) June 26, 2020

The #SaharanDust has arrived in Galveston, Texas!

No spectacular, colorful sunrise this morning. @Plume_Labs says air quality has dropped to unhealthy levels at the coast.

We’ll have another #SaharanAirLayer live report at 8:30a EDT / 7:30a CDT on @accuweather pic.twitter.com/p9SgnGDAyx

— Bill Wadell (@BillWadell) June 26, 2020

#SaharanDust arriving in Panama City Beach Thursday evening. Looks like a scene from another planet!

: Jennifer McFarland | #flwx @wtvmweather @WTVM @StormHour pic.twitter.com/NK6npC2gsn

— Lauren Linahan (@LaurenWTVM) June 26, 2020

Sahara dust arrives in New Orleans#SaharanDust #SaharanAirLayer #DustPlume pic.twitter.com/vyuU8ikMVV

— Lizzie (@pi_lizzie) June 26, 2020

Wow. This #SaharanDust Is really hazy. . Downtown Houston is dusty today. Lol @abc13houston @WeatherRadarUS #houston pic.twitter.com/iPukgeGT9L

— Chi’Nese Henry Pre-k Collaborative Teacher (@chinesehenry) June 26, 2020

At 1pm the sun is still somewhat visible through this #SaharanDust near Tifton, GA. #Weather #Dust pic.twitter.com/PWNPLbQSCN

— RJ Byrne (@therjbyrne) June 26, 2020

#SaharanDust arrives in the US https://t.co/RGEcLc62pX pic.twitter.com/7dWxLbObKO

— KCTV5 News (@KCTV5) June 26, 2020

Did you notice the hazy skies? The #SaharanDust plume we've been watching for the past week has finally made it to the Gulf coast, as seen on satellite yesterday. Expect this to stick around for the next day or two before conditions begin to improve later this weekend. #MOBwx pic.twitter.com/LealSh8jJg

— NWS Mobile (@NWSMobile) June 26, 2020