You create a wild temperature fluctuation at a point you can see within range. For the duration, you create a cylinder that is 300 feet tall with a 100-foot radius centered on the chosen point. Within this cylinder, the temperature becomes freezing cold or unbearably hot. When you cast this spell, choose whether you will create a coldsnap or a heatwave in the area.   Coldsnap. Creatures within the affected area have their movement speeds halved and have disadvantage on Dexterity ability checks and saving throws. When you cast this spell, and again as an action on each of your turns until the spell ends, you can choose a point within the cylinder. Each creature within 10 feet of the chosen point must make a Constitution saving throw, taking 6d10 cold damage on a failed save, or half as much damage on a successful one.   Heatwave. Creatures within the affected area have disadvantage on attack rolls and on Wisdom ability checks and saving throws. When you cast this spell, and again as an action on each of your turns until the spell ends, you can choose a point within the cylinder. Each creature within 10 feet of the chosen point must make a Constitution saving throw, taking 6d10 fire damage on a failed save, or half as much damage on a successful one.