It is purported to be “the Black Friday of airfares.”

National Cheap Flight Day is upon us, and unlike National Margarita Day, National Cheese Pizza Day, and National Pork Belly Foie Gras Blintzes Day, this one might actually be worth paying attention to. It is, according to historical data, the day the summer spike in airfares begins to cool down, and many airlines celebrate with some absolutely insane deals.

The “holiday” itself isn’t all that old, dreamed up a few years ago by Cheapoair when its people did some digging and found the year’s previous cheapest day for airfares was August 23.

“This begins the end of the summer season, and August 23 we’re gonna see a little bit better discounts than are typically out there,” says Tom Spagnola, Cheapoair’s global VP for supplier relations. “It’s just a day that fits. It’s not quite the end of summer, there’s a major holiday right after it, and now you get into some majorly cheap deals people can book.”

Because Cheapoair discovered it first, it has more or less led the charge on National Cheap Flight Day, arranging one-day-only deals with many of its partners in honor of this traditional flight low point. Spagnola said this year that Mexico, Thailand, and “the main European countries” will have the most eye-popping discounts. Though the site’s social media has also been teasing Argentina deals hard.

But is it really the cheapest day of the year to book flights? Or is it just a dressed up National Light Beer Day with better deals?

While historic airfare data is nothing to sneeze at, the deals it predicts might not be worth skipping work for, like three-for-one Tickle Me Elmos.

“It’s like the stock market,” says Scott Keyes, founder of Scott’s Cheap Flights. “In 2017 the single best day for stocks was March 1 when the Dow went up 300 points. But if your advisor had told you to invest all your money March 1, 2018, you’d have gone to bed very unhappy because stocks went down 400 points that day.”

Cheapoair’s data shows airfare has had a little more historic correlation than stock prices, though. Along a linear timeline, average airfares do, in fact, historically begin to drop from their summer highs on August 23, continuing into September and sometimes into October.

So while today may not be THE cheapest day of the year for airfares, it is at the very least the beginning of a welcomed trend.

Still, though averages may be dropping, average airfare isn’t always the best harbinger of when to find the best deals. Last year’s most headline-grabbing deal — an LA to Bali business class round-trip for $670 that usually sold for $4,500 — ran a week before National Cheap Flight Day. And Keyes says “average” does not always equate to “cheapest.”

“We don’t want average flights, we want cheap flights,” he says. “Say you have tickets for sale for $400 and $500 today, and the average is $450. Then tomorrow I have tickets for $300 and $900, and the average is $600. Studies that look at averages would say the second day is worse, but you and I know that the second day is when we can get $300 flights. And there’s no way to predict when that happens.”

That’s not to rain on your National Cheap Flight Day parade. That’s just to say if you somehow get slammed at work today and aren’t able to scour Cheapoair for its one-day-only deals, all is not lost.

“My advice is don’t focus too hard on any given day as predictive,” says Keyes. “People say National Cheap Flight Day is the cheapest day to book, but there are a lot of respectable days to book.”

Even Spagnola concedes there may be deals down the road, too.

“We’ve been able to achieve better deals in this one-day window,” he says. “But of course, if we get to early November and the airlines can see they’re struggling, you’ll see some pretty aggressive fares.”

Still, a giant, one-day, industry-wide fare sale is at least worth taking some time to browse. And if you, like many people, have an abundance of time on a summer Friday, both Spagnola and Keyes recommend booking a great deal as soon as you see it. You’ll still have 24 hours to cancel, which gives you enough time to weigh your buyer’s remorse and see if anyone else wants to go with you.

“General rule of thumb is the better the fare the shorter it’ll last,” says Keyes. “So it’s best not to dawdle.”

Even if you do dawdle, and you miss out on that dream $400 trip to Thailand, don’t let it drag your weekend down too much. Sunday is National Banana Split Day, after all, so you’ll still have that to look forward to.