Southwest's three-day sale ends Thursday: What you need to know to score cheap tickets

Time flies when you're trying to snag cheap plane tickets.

Thursday marks the last day of Southwest's semi-annual mega-fare sale, meaning time is running out for travelers to snag round-trip tickets as low as $98 on short flights.

The fall fare sale, which covers travel between Aug. 20 and Dec. 18, excluding Labor Day and Thanksgiving, features one-way fares of $49, $79, $99 and $129 depending on the route. Those fares are the starting sale prices and ticket prices vary greatly by date of travel.

The promotion is designed to fill seats during the slow travel period after summer vacation season and before the busy year-end holiday and school break travel rush. Tickets must be purchased by Thursday.

The prices are similar to the 2018 fall fare sale, but this year, the airline is allowing customers to travel six days further into December. (Last year's cutoff date was Dec. 12.)

Southwest's other big fare sale comes in early October.

The (significant) fine print of Southwest's three-day late summer/fall fare sale

  • Summer travel is largely excluded unless you can get away on or after Aug. 20. Forget about Labor Day weekend. It will be blacked out.

  • Forget about Thanksgiving travel, too. Sale fares are not available between Nov. 22 and Dec. 2.

  • Not all cities are included, and nonstop flights are required in many cases.

  • Friday and Sunday travel is excluded on most routes, ruling out quick weekend getaways.

  • Sale fares to Las Vegas and most cities in Florida, big vacation destinations, are limited to Sundays-Wednesdays, and return trips are only allowed Tuesday through Friday. So forget about snagging a deal for a weekend bachelor party in Vegas.

  • Deals on international flights are limited to Tuesday and Wednesday travel.

  • Travel to and from San Juan, Puerto Rico, is limited to Monday through Thursday, which means cruise passengers hoping to score a cheap flight to the city's port are out of luck.

Here's a sampling of where you can go for $49 one way:

Atlanta-Nashville

Phoenix-Las Vegas

Chicago-Nashville

Here's where you can go for $79 one way

Kansas City, Missouri-San Antonio

Portland, Oregon-San Diego

Baltimore-Minneapolis

Here's where you can go for $99 one way

Washington, D.C. (Reagan National Airport)-New Orleans

Dallas Love Field-San Jose, California

Here's where you can go for $129 one way

Boston-St. Louis

Houston (Hobby Airport)-Oakland, California

Wondering about deals on Southwest's new Hawaii flights? You won't find the blockbuster $49 one way tickets from California that Southwest used to launched the service in March. As of Tuesday, the cheapest fall fares between Oakland or San Jose and Honolulu are $159 each way, with scattered availability, mostly on Mondays and Tuesdays.

Booking tips for Southwest's three-day fare sale

1. Use Southwest's low-fare calendar to search for dates with the lowest fares. You might even find a few with fares lower than the sale rates.

2. Shop other airlines. Carriers tend to match, or even undercut, each other's fares on competing routes during a sale. Search prices on airline websites, online travel agencies or travel search sites.

3. Do you tend to travel with a lot of luggage? Factor in the cost of bags on other carriers. The biggest U.S. carriers typically charge $30 each way for the first checked bag and $40 for the second. Discounters like Spirit and Frontier charge varying prices. Southwest allows two free checked bags.

3. Find a sale price one way but not on the return leg? You can combine the two for a round-trip ticket and still save money. Or book two one-way tickets: fly Southwest one way and another carrier on the return.

4. Worried about booking a fall flight this far in advance? Southwest won't refund your money on its cheapest fares, but it will issue a credit to be used on a future flight by the named passenger. (In other words, you can't book a cheap flight between Los Angeles and Chicago during the sale, then cancel it and use the money for your kid's trip home from college.)

Still looking for a summer flight deal? Today is a popular day to shop

Even though Southwest's sale will exclude most summer travel, especially for families with school-age children, the high-profile sale still prompts a plethora of travelers to book summer travel on the first Tuesday of June, according to Hipmunk.

The travel search site looked at historical data for summer travel bookings and found that there are 90 percent more summer flight bookings on the first Tuesday in June than other days from June-August, so it dubbed today "Summer Travel Tuesday.'' (Southwest bookings are not included in Hipmunk's data because Southwest only sells tickets directly on its website or through its reservations center.)

Hipmunk spokeswoman Kelly Soderlund attributed the spike in bookings to the "halo effect'' of the Southwest sale, which is usually the first Tuesday in June, and summer promotions from other airlines.

More on Southwest:

Southwest Airlines User's Guide

Flying Southwest to Hawaii: Coconut rum, snack packs and "Forgetting Sarah Marshall''

Southwest is eliminating paper ticket jackets

This article originally appeared on USA TODAY: Southwest's three-day sale ends Thursday: What you need to know to score cheap tickets