Dire Winter (COA)

Upon casting this spell, the region plunges into a chilling winter.  The temperature drops below freezing, snow begins to fall, and bitter winds blow in a 1000 mile radius from the target area.  Any creature exposed to this cold must succeed on a DC 10 Constitution saving throw at the end of each hour or gain one level of exhaustion. The DC increases by 1 every additional hour in the climate. Creatures with resistance or immunity to cold damage automatically succeed on the saving throw, as do creatures wearing cold weather gear (thick coats, gloves, and the like) and creatures naturally adapted to cold climates.  This winter lasts 2d12 years.