The latest sale from Frontier is one of the best we've seen. They have priced over 50 routes at just $39 round-trip and also have another 100+ routes under $80 round-trip with their 90% off* (base fare) promo code.
Availability is limited so you must be somewhat flexible to find the lowest price. Travel days will vary by route. Many routes start service the second week of April and have limited frequencies so be sure to check out the specifics in the fare details on your route.
The $39 round-trip fares are not advertised with an expiration date so they may jump in price at any time. Travel is valid on select dates through May 9. If you use the promo code listed below, you may be able to knock $1 off each way for travel on Tuesdays or Wednesdays, but these fares are available more days/week without the promo code.
A sample of nonstop $39 round-trip fares include:
Frontier also has a promo code valid for Tuesday and Wednesday travel from April 4 through May 16. Using the promo code SAVE90 on FlyFrontier.com will discount 90% off the base fare for nonstop domestic flights on those specific dates.
Many routes may only be operated on limited days each week. If you can't travel for a full week, you can use the promo code one-way to save on a portion of your trip. Promo code expires at 11:59 pm ET, on March 23.
A sample of nonstop promo code fares include:
The discount does not apply to taxes nor Frontier's online booking fee, which they label a "Carrier Interface Charge". This means some routes still won't have a very big price drop, but most will. As always, Frontier has a long list of specific routes that are excluded from the promo code sale.
These fares all work in reverse and there are many more routes priced under $80 round-trip as well. Check what's available from your city. Keep in mind that Frontier charges extra for any bags larger than a small personal item (small backpack, purse, etc.). Pack super light to get the lowest price. Checked bag fees start at $25 each way.