Storms Sunday night blew in strong winds, dust and of course that foul stench you might've gotten a whiff of.
"It just smells gross. Like rotten eggs," said Alphie Moreno, of Indio.
The smell didn't stop Lisa Salisbury and her family from heading out to the Palm Desert Civic Park Monday night.
"It's a little muggy right now, but I like the cool down. The smell I could do without," she said.
Investigators from the South Coast Air Quality Management District are out tracking the stench after being flooded with hundreds of complaints and 911 calls. The big question: Where is it coming from?
"My friend said it's coming from the Salton Sea," said Moreno.
Investigators believe that's one theory. The smelly phenomenon is known to occur this time of year when large amounts of fish die off and decay. The Salton Sea authority says weather could be to blame.
"The problem that you get is, last night we had a wind storm out here and the Salton Sea is very shallow. The wind can stir the Salton Sea up and brings up gases off the bottom of the sea," said Andrew Schlange, of the Salton Sea Authority.
However, what's unusual is for the smell to spread and hover as far west as Los Angeles.
''Sulphur smells could come from a large body of water when you have an algae bloom or a fish kill. It could also come from a wastewater treatment plant. Those are the kinds of things you would think about with this kind of smell," said Sam Atwood, of the South Coast Air Quality Management District.
In Los Angeles, firefighters issued a statement saying residents did not need to call 911 to report the stink. Also, at least one elementary school canceled recess because of the intense smell.
The cause may be unclear for now but some neighbors in the Coachella Valley are confident they have the answer for those people unfamiliar or shocked by the rotten smell.
"If it's hitting out there, they're not used to it. I can understand. We know what it is. Hopefully it is the Salton Sea," said Salisbury.
Experts say the mysterious smell doesn't pose any health hazards.