This is one of the best promo code sales on Frontier that we've seen in a while. Take up to 90% off the base fare for travel this fall and 75% off the base fare for winter travel. Fares start at just $37 roundtrip.

Use promo code SAVE90 when booking on to take 90% off the base fare for nonstop domestic flights on Mondays, Tuesdays, Wednesdays, Thursdays, and Saturdays, from September 5 through October 4. Use promo code SAVE75 to take 75% off the base fare travel on Tuesdays, Wednesdays, and Saturdays, from October 6, 2018, through February 13, 2019. Avoid blackout dates November 15-28, and December 15, 2018, through January 5, 2019.

The discount does not apply to taxes nor Frontier's online booking fee, which is labeled a "Carrier Interface Charge". This means some routes still won't have a very big price drop even with the big sticker shock of 75-90% off. However, there are plenty of routes where we are seeing deep discounts. 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 route exclusions for both the 90% off and the 75% off promo code sales. You may have to click around to find available dates since Frontier operates about half of the route network on just a few days each week. Click on the fare details for more info on exact dates each route is available.

Tickets must be booked by 11:59 pm ET, on August 29, 2018.

A sample of nonstop routes, which work with both sales (Lowest fare is for the 90% off sale)

Atlanta to Orlando $37 roundtrip

Greenville to Orlando $39 roundtrip

Harrisburg to Orlando $41 roundtrip

Portland, ME to Orlando $41 roundtrip

Syracuse to Orlando $41 roundtrip

Cincinnati to Dallas $50 roundtrip

Omaha to Las Vegas $68 roundtrip

Raleigh to Las Vegas $70 roundtrip

St. Louis to Las Vegas $70 roundtrip

Raleigh to San Diego $70 roundtrip

Cincinnati to Los Angeles $72 roundtrip

Philadelphia to San Juan $101 roundtrip

A sample of nonstop fares that work only with the 90% off promo

Cleveland to Orlando $41 roundtrip

Norfolk to Las Vegas $56 roundtrip

Buffalo to Orlando $70 roundtrip

Denver to Miami $70 roundtrip

Pittsburgh to San Diego $72 roundtrip

Columbus to Denver $74 roundtrip

New York to Atlanta $74 roundtrip

A sample of nonstop fares that work only with the 75% off promo

Providence to Tampa $69 roundtrip

Philadelphia to Miami $72 roundtrip

Minneapolis to Denver $72 roundtrip

Chicago to Harlingen $74 roundtrip New route announced today!

Denver to Harlingen $74 roundtrip New route announced today!

New York to Orlando $79 roundtrip

Phoenix to Raleigh $79 roundtrip

Albany to Orlando $82 roundtrip

Atlanta to Los Angeles $89 roundtrip

Many more routes are available and these fares all work in reverse 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 $25 each way. Larger carry-on bag fees start at $30 each way.

Above image by Colin A. Pierce via Shutterstock.

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