You think you’re crafty leaving the Thursday before Thanksgiving, assuming the airport will be nothing but you and some lonely Starbucks baristas.

Then you get half a mile from the drop-off area and traffic’s stopped. Check-in takes an hour. Security is another hour. You need to put Icy Hot on your shoulder because it’s so sore from carrying the 70 pounds of luggage you packed into a “carry-on” duffle. Looks like you weren’t the only one who thought you were being crafty.

The thing about airport traffic is that it’s about as unpredictable as airfares. Sometimes you show up on a Friday at 6:00 PM and breeze right through. Sometimes you book a Wednesday lunch flight and it feels like all of Cincinnati did too. You might have better luck picking horse races, who knows?

Well, actually, some people do know. We got numbers from the good people at Skyscanner, the travel app that tracks historic airfares and plane loads, as well as AirHelp, the “world’s leading air passenger rights company,” to help find the busiest days at the airport in 2017. Which, hopefully, shows trends around the same times to watch for this year and into 2019.

Some are predictable, but others might surprise you, and at the very least, keep you from an unexpected long day at the airport.

Note: All travel dates and corresponding holiday dates are from 2017.

May 26th (Friday before Memorial Day) — No huge shock here, other than that it’s busier than Memorial Day itself. Maybe take an extra vacation day and leave a day early, or head out early Saturday morning.

June 30th (Friday before the Fourth of July) — In 2017, the Fourth was a four-day weekend. So plenty of people headed out on the Friday prior, making it the third busiest airport day of the year. Again, not a surprise, but look for July 3rd to be insanely crowded in 2019 ahead of another four-day weekend.

August 31st (Thursday before Labor Day) — Think you’re slick dipping out a day early on the first weekend of football season? Think again. AirHelp found this to be the second-busiest day of Labor Day weekend.

September 1st (Friday before Labor Day) — It’s the second busiest day of the year to fly, and the busiest before November. Perhaps a nice barbecue at home is in order.

November 10th — This may have been the first travel shocker of the year, as the second Friday in November was the busiest day of the entire month and that includes Thanksgiving. Either there were a LOT of people traveling for that big UConn/Central Florida game in Orlando, or everyone wanted one last weekend away before going to see the family.

November 17th (Friday before Thanksgiving) — The Friday before Thanksgiving week has become an increasingly popular day to travel, as many schools now give the entire week off, and parents are willing to take an extra few vacation days to avoid the Thanksgiving crush. The Saturday and Sunday before Thanksgiving, however, bottom out. So maybe wait a day or two if you’re planning to leave for a week.

November 22nd (Day before Thanksgiving) — Urban legend says this is the nastiest travel day of the year, but it’s actually not even the worst in November, and only the sixth busiest of the year. That’s not to say expect Thanksgiving eve to be a breeze in 2018. But don’t let it scare you too much.

November 26th (Sunday after Thanksgiving) — Another predictably busy day at the airport, as AirHelp found this to be the busiest day of the Thanksgiving travel season.

November 30th — Another surprise for those who took a full week for Thanksgiving to avoid the masses. It’s not slammed like other November dates, but saw a significant uptick in Skyscanner’s numbers from the week following Turkey Day.

December 22nd (Friday before Christmas) — The nightmare before Christmas is truly any airport on the Friday prior, the 2017 undisputed champion of busiest days to fly. It saw nearly double the traffic of the day before Thanksgiving, and quadruple some dates in February. Wait until the next day and that number drops in half.

January 2nd — This was the busiest day of the year for “return home” flights, gauged as the back half of round trips. If you’re okay with flying with a hangover, you can avoid a lot of trouble by leaving on January 1st.