The latest sale from Frontier includes around 30 routes priced at just $20 one-way and roundtrip fares are as low as $34. A few other routes have dropped to $57 roundtrip for fall travel.

If you're unfamiliar with Frontier Airlines and how this ultra-low-cost carrier differs from other airlines, read up on Everything You Need to Know Before You Fly Frontier.

Availability is limited so you must be somewhat flexible to find the lowest price. Travel days will vary by route, but generally, fares are available through mid-November or mid-December, with a 7-day advance purchase required. Avoid blackout dates between November 16-26. Pretty much all of these routes are only flown a few times each week so be sure to check out the specifics in the fare details on your route.

Tickets must be booked by 11:59 pm ET, on September 19, or before seats sell out.

A sample of nonstop fares include:

Greenville to Orlando $34 roundtrip

Charlotte to Orlando $37 roundtrip

Salt Lake City to Las Vegas $39 roundtrip

Orlando to Atlanta $39 roundtrip

Las Vegas to Sacramento $39 roundtrip

Philadelphia to Charleston $39 roundtrip

Knoxville to Orlando $39 roundtrip

Birmingham to Orlando $39 roundtrip

Raleigh to New Orleans $39 roundtrip

Chicago to Harlingen $39 roundtrip

Colorado Springs to Chicago $39 roundtrip

Denver to Wichita $39 roundtrip

Denver to Tucson $39 roundtrip

New Orleans to San Antonio $39 roundtrip

San Antonio to Albuquerque $39 roundtrip

Charlotte to San Antonio $55 roundtrip

Buffalo to Orlando $57 roundtrip

Cincinnati to Minneapolis $57 roundtrip

Cincinnati to Denver $57 roundtrip

Norfolk to Tampa $57 roundtrip

Buffalo to Austin $57 roundtrip

St. Louis to Jacksonville $57 roundtrip

Trenton to Fort Lauderdale $57 roundtrip

There are plenty more routes priced under $100 roundtrip and these fares all work in reverse as well. 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, purse, etc.). Learn How to Pack in Just a Personal Item Sized Bag 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 complete look at baggage fees on all airlines, check out our Bag Fee Chart. 

Header image by Colin A Pierce via Shutterstock.