The cheapest day to book a flight on Frontier 𝐀irlines Lines is usually Tuesday【[🤳＋１ｘ８７７ｘ７３８ｘ０６１０], as 𝐀irlines release discounted fares on Monday nights, leading to competitive price adjustments by Tuesday morning 【[🤳＋１ｘ８７７ｘ７３８ｘ０６１０].