Frontier is having another high percentage promo code discount for purchase through midnight ET, tonight. Save up to 90% off the base fare on your next Frontier flight for winter travel. This sale includes a few routes that are normally excluded from Frontier's promo code sales. Fares start at just $38 roundtrip.

Use promo code SAVE90 when booking on FlyFrontier.com to take 90% off the base fare for nonstop domestic flights from December 8, 2018, through February 6, 2019, excluding Sundays. Additional blackout dates apply: December 20, 2018 - January 6, 2019; January 17-18, 21-22, 2019.

Even though Sunday travel is excluded from this promo code sale, you may still be able to score a long weekend travel deal departing on a Friday, and returning on a Monday.

While the promo code does not apply to taxes nor Frontier's online booking fee, which is labeled a "Carrier Interface Charge", the fact that it does take 90% off the base fare means that these are the some of the lowest fares we ever see on many routes. Occasionally, Frontier has lower fares with flash sales on less popular routes when it eliminates or lowers the online booking fee, but the most popular routes rarely dip this low. The discount can also be applied to one-way flights.

If you are unfamiliar with Frontier Airlines, please read our guide on Everything You Need to Know Before You Fly Frontier.

There are specific routes excluded from this promo code sale. You also may have to click around to find available dates since Frontier operates about half of its route network on just a few days each week, and the schedule can change from month to month. Click on the fare details for more info on exact dates each route is available.

Tickets must be booked by 11:59 pm ET, December 7, 2018.

A sample of nonstop fares include:

Atlanta to Orlando $38 roundtrip

Greenville to Tampa $38 roundtrip

Atlanta to Miami $43 roundtrip

Charlotte to Tampa $48 roundtrip

Albany to Orlando $50 roundtrip

Philadelphia to Miami $50 roundtrip

Syracuse to Orlando $50 roundtrip

Minneapolis to Denver $50 roundtrip

San Francisco to Las Vegas $50 roundtrip

Chicago to Tampa $51 roundtrip

Buffalo to Orlando $59 roundtrip

Milwaukee to Denver $60 roundtrip

Minneapolis to Tampa $68 roundtrip

San Antonio to Las Vegas $68 roundtrip

Austin to Philadelphia $68 roundtrip

Austin to Santa Ana $68 roundtrip

Denver to Dallas $68 roundtrip

Tampa to Las Vegas $69 roundtrip

New York to Miami $69 roundtrip

Chicago to Miami $70 roundtrip

Detroit to Orlando $70 roundtrip

Cleveland to Denver $70 roundtrip

Denver to Philadelphia $71 roundtrip

Indianapolis to San Diego $71 roundtrip

Cincinnati to Phoenix $72 roundtrip

Cleveland to San Diego $72 roundtrip

Denver to Sacramento $72 roundtrip

Atlanta to Las Vegas $73 roundtrip

Cincinnati to San Diego $73 roundtrip

Milwaukee to Las Vegas $73 roundtrip

Columbus to Denver $74 roundtrip

Raleigh to San Diego $74 roundtrip

Pittsburgh to Denver $76 roundtrip

Norfolk to Las Vegas $78 roundtrip

Orlando to San Juan $97 roundtrip

These fares all work in reverse and there are many more routes available as well. Lowest fares may not be available throughout the entire travel period. You'll have to decline all extras to get the lowest price.

Keep in mind that Frontier charges extra for any bags larger than a small personal item (small backpack, large purse, etc.). Pack super light to get the lowest price. Checked bag fees start at $30 each way. Larger carry-on bag fees start at $35 each way.

If you want to avoid all extra fees, read How to Pack in Just a Personal Item Sized Bag.

As an example booking, after entering promo code SAVE90 on FlyFrontier.com, I found seats departing Chicago ORD on Friday, January 11, returning from Miami MIA on Monday, January 14, for $78 roundtrip. Perfect for a winter weekend getaway. Slightly lower fares are available for mid-week travel.

Header image via Shutterstock.