Winds of Combustion

You transmute the air in a 5-foot diameter, 20-foot long line originating from a point of your choice within range into a highly combustible gas. If an open flame, effect that deals fire damage, or spell that deals fire damage passes through or enters the line, the gas explodes. Each creature within 5 feet of the line when it explodes must make a Dexterity saving throw. On a failed save, a creature takes 1d8 thunder damage, 2d6 fire damage, and the spell ends. On a successful save, it takes half as much damage.

 A strong wind of 10 mph or greater disperses the gas early, ending the spell.

At higher levels. When you cast this spell using a spell slot of 2nd level or higher, the fire damage increases by 1d6 for each slot level above 1st.