To take part in these cheap fares, book by midnight ET on February 2 for travel between February 8 and March 14.
Though, be aware that Frontier is a budget airline and has the fees to prove it. You'll get dinged for luggage and for seat selection. However, you get a personal item for free and can skip the seat reservation fee by having your seat assigned to you at the airport. (You should also note that Frontier's on-time arrival rate is about as good as the MTA's.)