Thunder only happens when it's raining, and Stevie Nicks is only playing a guest role on "American Horror Story: Coven." But for fans of either the FX series or Fleetwood Mac's resident sorceress, it's still exciting news. 

Executive producer Ryan Murphy tweeted Tuesday: "Guess who's visiting the Coven? The legendary Stevie Nicks!"

A spokesman for FX confirmed that the pop singer will do a guest spot on the show. Some reports suggested Nicks would play herself, but the spokesman said he had no details about what role she might play.

PHOTOS: Unexpected musical collaborations

But one clue: the "Coven" character of Misty Day (Lily Rabe) worships Nicks, so there's an obvious tie-in right there. Nicks has denied for years that she is a follower of Wicca but stories still linger. In fact, Nicks' Wikipedia page includes a section titled: "Rumors of Witchcraft."

"AHS" would count as a rare scripted-TV appearance for the 65-year-old Nicks, the scarf-clad songwriter behind "Dreams," "Edge of Seventeen" and other hits. But she has appeared in guest or mentoring roles on music shows such as "American Idol" and "The X Factor."

"Coven," which stars Jessica Lange and is scheduled to conclude in January, is the third season in the "American Horror Story" franchise. It's averaging 4.3 million total viewers per episode, according to Nielsen.

What do you think of Nicks and her upcoming "AHS" part?

ALSO:

Donnie and Mark Wahlberg team up for A&E reality series

Does Charlie Sheen really want to make nice with Chuck Lorre?

Alec Baldwin's MSNBC talk show 'Up Late' sinks to new low in ratings