Here's a great promo code sale on Frontier that is available for purchase through the weekend. Take 90% off the base fare for travel through mid-December. Fares start at just $45 roundtrip.

Use promo code SAVE90 when booking on FlyFrontier.com to take 90% off the base fare for nonstop domestic flights on Tuesdays, Wednesdays, and Saturdays, through December 18, 2018. A 7-day advanced purchase is required and there are blackout dates on October 6, 13, 20, and November 17-27.

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 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 and how the airline differs from other carriers, please read our guide on Everything You Need to Know Before You Fly Frontier.

There are specific route exclusions that won't work for this promo code sale. Also, 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. If your search results in an error due to nonstop flights not being offered on the dates you're searching, you'll have to re-do your search in order for the discount to apply. Click on the fare details for more info on exact dates each route is available.

Tickets must be booked by 11:59 pm ET, September 17, 2018.

A sample of nonstop fares include:

Greenville to Orlando $45 roundtrip

Charlotte to Orlando $48 roundtrip

Salt Lake City to Las Vegas $50 roundtrip

Syracuse to Orlando $56 roundtrip

Harrisburg to Orlando $57 roundtrip

Providence to Tampa $68 roundtrip

Long Island-Islip to Orlando $69 roundtrip

New York to Orlando $70 roundtrip

New York to Miami $70 roundtrip

Philadelphia to Miami $70 roundtrip

Minneapolis to Denver $70 roundtrip

Denver to Washington D.C. $70 roundtrip

Denver to Harlingen $70 roundtrip

St. Louis to Las Vegas $71 roundtrip

Raleigh to Phoenix $72 roundtrip

Portland to Denver $72 roundtrip

Fort Myers to Las Vegas $72 roundtrip

Orlando to Ontario, California $72 roundtrip

Huntsville to Denver $73 roundtrip

Portland, ME to Orlando $74 roundtrip

Denver to Atlanta $74 roundtrip

Columbus to Denver $74 roundtrip

Cleveland to Las Vegas $74 roundtrip

Denver to San Diego $74 roundtrip

Lafayette to Denver $74 roundtrip

Madison to Phoenix $74 roundtrip

Denver to New Orleans $76 roundtrip

Philadelphia to Denver $76 roundtrip

Washington D.C. to Las Vegas $78 roundtrip

Atlanta to Las Vegas $79 roundtrip

Denver to Providence $79 roundtrip

Orlando to San Juan $106 roundtrip

San Juan to Philadelphia $106 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 and may go up in price over the weekend. 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.

For a look at baggage fees across all airlines, check out our updated Bag Fee Chart.

Above image by Colin A. Pierce via Shutterstock.