A storm cloud appears in the shape of a cylinder that is 10 feet tall with a 60-foot radius, centred on a point you can see within range directly above you. The spell fails if you can’t see a point in the air where the storm cloud could appear (for example, if you are in a room that can’t accommodate the cloud).

When you cast the spell, choose a point you can see under the cloud. A bolt of lightning flashes down from the cloud in a 5-foot-radius cylinder directly under the cloud. Each creature within the cylinder must succeed on a Dexterity saving throw or take 3d12 lightning damage. On each of your turns until the spell ends, you can use your action to call down lightning in this way again, targeting the same point or a different one.

When you call a lightning, you can ignite flammable objects and structures where it strikes that aren't being worn or carried.

If you are outdoors in stormy conditions when you cast this spell, the spell gives you control over the existing storm instead of creating a new one. Under such conditions, the spell’s damage increases by 1d12, and you can call down the lighting at any point you can see under the storm.

At Higher Levels. When you cast this spell using a spell slot of 4th or higher level, the damage increases by 1d12 for each slot level above 3rd. When you cast the spell with a spell slot of 6th level or higher, the spell’s duration becomes 1 hour (concentration) instead.