Each of the holiday-based vendors that appears by the fountain in the Shopping District has a specific school of magic that the gear they sell is suited for.
Valentina Heartsong: Fire Pat-'o-Gold: Life Eggbert: Myth Spooky Bob: Death Harvest Hannah: Balance Felix Navidad: Ice
As you can see, Storm is missing from this list. I think the only major holiday without a vendor is the 4th of July, so in the interest of not showing least-favorites, I think you have plenty of time to develop a shop inventory for a new vendor.
