The Rise of Air Travel Cost?

We will fly back to North Carolina in this coming Sunday and resume the project. When we checked the air tickets to NC, it was more than $400 bucks for a round trip ticket. Why the cost for air ticket suddenly rise so high? Is it because of the coming of summer? Or is it due to we book the air tickets in such a short time frame? Well, we finally found low fare round trip tickets from JetBlue. Yeah!