Rudolph and Frosty's Christmas in July (1979)

Long ago the Lady Borealis placed the evil Winterbolt under a magic spell, and put the last of her magic into the nose of a newborn reindeer: Rudolph. But now Winterbolt's awake.

He gives Frosty's family magic amulets to keep them from melting until the Fourth of July so that Frosty and Rudolph can help Lilly's circus and Milton can marry his girlfriend on the high-wire, and Santa will use his sleigh to make sure everybody gets back to the North Pole in time.. which leaves Winterbolt alone at the North Pole on the Fourth.