The Flame of the North by Anna Tan

Ten-year-old Mica hates the cold. Yet he’s bound by duty—and prophecy—to rule over the City of Winter as his grandfather’s heir. All signs seem to indicate that something is wrong and the reappearance of the Yuki-Onna in the Painted Hall is an additional worrisome detail… The Flame of the North (North #2) follows Danis & Hana’s son as he attempts to fulfil the last portion of Dragon’s Prophecy.