Goulburn, Australia, residents woke to a creepy phenomenon on May 13 as millions of spiders "rained" on the New South Wales town, reports the Goulburn Post.

"They fly through the sky and then we see these falls of spider webs that look almost as if it's snowing," South Australian retiree Keith Basterfield told the Goulburn Post.

"Anyone else experiencing this 'Angel Hair' or maybe aka millions of spiders falling from the sky right now? I'm 10 minutes out of town, and you can clearly see hundreds of little spiders floating along with their webs and my home is covered in them. Someone call a scientist!" a resident named Watson wrote on the Goulburn Community Forum Facebook page.

Live Science magazine did exactly that. The magazine called retired arachnologist Rick Vetter at the University of California to find out if he could explain the phenomena. Vetter said that Watson and his neighbors probably witnessed a form of spider transportation known as ballooning.

"Ballooning is a not uncommon behavior of many spiders. They climb some high area and stick their butts up in the air and release silk. Then they just take off," Vetter told Live Science. "This is going on all around us all the time. We just don't notice it."

Todd Blackledge, a biology professor at the University of Akron in Ohio, said that while spider ballooning is common, it is uncommon for millions of spiders to perform the feat at the same time, or land in the same place. Weather conditions play a part; if the weather has been unfavorable for ballooning for quite some time, when it improves, lots of spiders disperse at once.  

In New South Wales, a certain species of small spiders and the tiny hatchlings of larger spider species are known to balloon during late autumn, which is in May, and early spring, which is in August. As Blackledge explained, an abrupt weather change or wind pattern may have caused the migrating spiders to travel down to the ground en mass -- not the dispersal that the spiders or Southern Tablelands region residents were expecting.