Drycloud

You create a 20-foot-radius sphere of magical air centered on a point within range. The sphere spreads around corners. It lasts for the duration or until a wind of moderate or greater speed (at least 10 miles per hour) disperses it. Every item within the sphere gains a vulnerability to fire, and is flammable. Every living creature while within the sphere is now also flammable, and must make a constitution save or gain vulnerability to fire damage. This effect goes away when the target is not within the sphere.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the radius of the drycloud increases by 20 feet for each slot level above 1st.