Frontier Airlines is also making major upgrades including UpFront Plus seating, which offers extra legroom and a guaranteed empty middle seat. Soon, top customers will enjoy unlimited free companion travel, and by late 2025, First Class seating will be available on all flights, keeping comfort high and prices low.

Frontier's summertime deal appears to be in response to Southwest Airlines, which recently announced it will start charging for checked bags.

Frontier Airlines took a swipe at Southwest Airlines’ plan to start charging for seat assignments and checked luggage by doing the opposite.