Update: Some offers mentioned below are no longer available. View the current offers here.For more TPG news and deals delivered each morning to your inbox, sign up for our daily newsletter here: https://thepointsguy.com/mailing-list//Low-budget airline Frontier is back with a mega flash sale, with one-way nonstop deals across the country starting as low as $20 or $39 round-trip. We’re even seeing deals to San Juan for as low as $97!Keep in mind that Frontier charges extra for everything from a carry-on bag to a seat assignment to a can of soda. Still, even if you choose to bring a full-size carry-on bag aboard your flight and lock in a specific seat, you will likely end up paying less than on full-service carriers. Also note that the dates you can fly vary by route, so make sure to click “About This Deal” before you book.If you want to book, we suggest you don’t wait as these fares expire at 11:59 PM on September 16!To search, head to Frontier’s website and enter your origin and destination cities. Scroll through the calendar function to find dates and prices that work for you. Finally, click through to book directly with the airline.Airline: FrontierRoutes: Major routes served by Frontier, see full list hereCost: $20 one-way, $39 round-tripDates: September – NovemberPay With: The Platinum Card® from American Express (5x on airfare booked directly with the airline), Citi Prestige® Card (5x on airfare), Citi Premier® Card, Chase Sapphire Reserve (3x on airfare), American Express® Gold Card (3x on airfare when booked directly with the airline) or Chase Sapphire Preferred Card (2x on travel)Here are a few examples of what you can book:Los Angeles (LAX) to Las Vegas (LAS) for $20 one-way:Sign up for our daily newsletterEmail addressSign upI would like to subscribe to The Points Guy newsletters and special email promotions. The Points Guy will not share or sell your email. See privacy policy.Austin (AUS) to Detroit (DTW) for $20 one-way:Atlanta (ATL) to Los Angeles (LAX) for $25 one-way:Denver (DEN) to New Orleans (MSY) for $25 one-way:Boston (BOS) to Orlando (MCO) for $36 one-way:Philadelphia (PHL) to Miami (MIA) for $36 one-way:New York (LGA) to Atlanta (ATL) for $36 one-way:Austin (AUS) to Tampa (TPA) for $39 round-trip nonstop:Atlanta (ATL) to San Juan (SJU) for $97 round-trip nonstop: