(at least thus far this year)
The Time Fetch by Amy Herrick, Algonquin Young Readers
As the winter solstice nears, the days get shorter. But what if the days were literally getting shorter as time was lost, forever? Edward doesn't believe in his aunt's new agey Solstice nonsense until the unthinkable happens. Annoying classmate Feenix disappears and no one seems to notice. Pumpkins decay in the course of a single class. And time has started disappearing. Though Edward would rather do the easy thing than the right thing, he and three classmates will have to venture into the snow if the world is to be put back into balance. Take the dimensional characters and realistic relationships from Rebecca Stead's books and mix with the strange magic of The Peculiar; the result is Amy Herrick's stunning middle grade debut.
I think it has Newbery potential.