JACKSONVILLE, Fla. -- Southwest Airlines is advertising one-way flights from August 22 to December 13 for as low as $49.

The story was shared nearly 400 times from our Facebook, but a lot of the comments were pointing out the sale's shortcomings: return flights can be expensive and getting the lowest price flight would require some flexibility or luck. So what's really up with this seemingly amazing deal?

For this sale, four routes are available from Jacksonville:

As expected not every date, at every time, is available for the discounted rate. The sale is also restricted to week days only.

Flights from Jacksonville to Atlanta start at $49, but you have to be choosey about what dates you will be traveling. On Friday, August 25 at 1:15 p.m. the flight to Atlanta will cost you $146 as opposed to the advertised $49, however the time slots before and after 1:15 p.m. are listed at $49. November 25 - 27 tickets are $293, at the least expensive.

Return flights suffered from the same pricing inconsistency. Some flights on some days were into the hundreds of dollars, while on the same day, other flights were only $49.

Perhaps most notably, not all days are available for a discounted rate at all.

If you're looking for a flight to Baltimore, Maryland from Jacksonville you can find weekend days for return flights listed at $99, which is lucky, if those dates work out for you. Flexibility is key when it comes to taking advantage of these low prices.

Headed to Houston? Well you won't be able to take advantage of the $99 ticket until more than a week after the sale begins. Unfortunately, some return flights can be up up to $259; one return flight is $327, so try not to fly back to Jacksonville on November 25-27.

Similar to Houston departing flights, you won't snag at $79 flight to Nashville until August 22 and prices throughout the time period vary from $79 - nearly $200.

The moral of the story is to be flexible. Take the time to check each date and time to make sure you are getting the lowest cost. If you have to fly out or back on a weekend day, you may want to search other airlines.

A great way to find the cheapest flight on any given day is to use the "Low Fare Calendar" which does all the research for you.

We tried Google Flights to try and assess the cheapest airfare days, but it appears that during the sale Southwest's prices were not appearing on the site. However, websites like Google Flights that compare many airlines prices may be a good resource if you are looking for a one way ticket to complement your Southwest bargain ticket.