Cheap Days to Fly with Frontier Airlines Discover the cheapest days to fly with Frontier Airlines! Save money on your next trip by planning your travel on days with the lowest fares. Get tips on when to book and fly to maximize your savings. You can know more about the cheapest days through the official website or by dialing the Frontier Airlines customer service number. For more details, you can also visit: https://www.airflyreservations.com/blog/what-are-the-cheapest-days-to-fly-on-frontier-airlines