A bit underwhelming if there are no minions in play, but if there is a minion in play somewhere it's decent, and if any player has two or more engaged minions it's very good.

Note that unlike Storm's other three big events (Lightning Bolt, Flash Freeze, Torrential Rain), this one will give you your weather effect regardless of what the weather is. Drawing a card, two damage/threat, or blanking a minion could all be very relevant. Also, this isn't an attack, so you don't have to worry about Retaliate or being stunned.

In a handful of scenarios there is more than one Villain. Carefully read these scenarios rules. In many cases (example The Wreaking Crew), there a clear statement: "Card that target the Villain, targets the Active Villain, not all Villains in play".