If you're planning to leave town for Memorial Day weekend, you have a lot of company. About 45 million Americans are going to do just that between May 21 and May 25, and most of them haven't run the numbers on how much it will cost.

I have, and it's more than you think.

This will be the busiest Memorial Day weekend on record, according to AAA. A record 39.1 million people will travel by car. Another 3.66 million will fly. And 2.2 million more will take a bus, train, or cruise. The roads will be jammed, the airports will be a mess, and the price you pay for the privilege of sitting in traffic will be significantly higher than it was last year.

That's the part no one in the travel industry wants to lead with. So let's lead with it.

AAA's announcement frames this weekend as a celebration of "the unofficial start of summer." Yeah, right. It's also the start of the most expensive driving season in three years.

Pump prices are the highest they've been since the summer of 2022. Last Memorial Day, a gallon of regular cost $3.17 on average. This year, drivers are paying $4.53, a 42 percent increase.

Allstate's data adds another layer the industry tends to skip. According to figures the insurer shared with me, the average drive over Memorial Day weekend runs about 9 percent longer than on a typical spring weekend. Last Memorial Day weekend alone, AAA responded to more than 350,000 emergency roadside calls.

"Longer trips don't just wear on drivers, they put more strain on vehicles too," said Brian Dieringer, president of Allstate Roadside. "The more time you spend behind the wheel over a holiday weekend, the more likely you run into a problem."

Translation: the longer you drive in heavy traffic at high speeds, the better the odds you'll be the one on the shoulder waiting for a tow. We had a lively discussion about road trip dangers on Friday.

INRIX, the transportation data company, has crunched the metro-by-metro congestion forecast, and a few of the numbers are troubling. The worst delays are expected on the journey from Boston to Manchester, N.H., on Monday around noon, which is expected to take an estimated 1 hour 36 minutes, a 123 percent increase compared to typical travel time. Other major expected delays include the journey from the Jersey Shore to New York on Monday at 1 p.m., which is estimated to take 2 hours 24 minutes (92 percent longer), and Los Angeles to Bakersfield on Friday at 5 p.m., which is estimated to take 3 hours 36 minutes (83 percent longer).

Sunday, oddly, is the lightest day for traffic, but almost no one talks about that. 

If you booked your flight early, you probably got a deal. AAA says roundtrip domestic flights are 6 percent cheaper than last year. But that figure reflects what people paid when they booked, before jet fuel prices started climbing. If you're buying now, expect to pay more.

A note on rental cars: AAA's partner Hertz says Thursday and Friday are the busiest pickup days, and the highest-demand markets are Orlando, Las Vegas, Los Angeles, Denver, and Boston. Rental rates are about 1 percent cheaper than last year, which is essentially flat. Don't expect a bargain.

Here's the advice the press releases won't give you straight.

I didn't want to lead with "worst Memorial Day ever!" but you get the idea. It's gonna be bad out there.

The takeaway: If you can move your travel to Sunday, do it. Everything is cheaper, emptier, and less likely to end with a tow.

There's some good news for summer airfare bargain hunters. New data from Kayak shows the cheapest stretch to fly is between August 10 and September 6, with domestic roundtrips averaging $365 and international fares averaging $761.

That's a roughly 9 percent savings on domestic flights and a 42 percent savings on international trips compared to flying earlier in the summer. 

Here are domestic airfares.

And here are international airfares.

The catch is obvious: Most families with school-age kids are already back home by then. Which is exactly why the seats are cheap.

Kayak's data, based on searches between March 1 and April 10 for travel between May 21 and September 8, also shows where Americans are actually looking. Domestic searches are up about 7 percent over last year, suggesting more travelers are staying close to home as international prices climb.

Nearly half of the most-searched flight destinations are averaging under $500 roundtrip. The cheapest:

On the international side, the bargains are in North America. Toronto averages $387, Mexico City $466, Calgary $472, and Cancún $494. 

Here's the part Kayak isn't talking about, probably because it doesn't want to upset its airline partners: The late-August window isn't cheaper because airlines are being generous. It's cheaper because demand collapses the moment school starts. 

If you can take your vacation in that window, you're effectively getting a discount for being childless, retired, or willing to pull your kids out of the first week of school. The airline isn't doing you a favor—it's filling seats it can't sell at full price.

The other thing worth flagging: These are average fares. The actual price you'll pay depends on when you book, which airport you fly out of, and whether you're willing to take a connection. The averages are useful as a benchmark, but they're not a guarantee.

The takeaway: If you have the flexibility, book a trip between August 10 and September 6. If you don't, you're paying a premium this summer.

The cruise industry had a rough week, as I noted in this morning's commentary. Viral outbreaks, accidents, and a CDC inspection program that's been gutted just in time for peak season. The industry's response? Discounts, drink packages, and a future cruise credit if anything goes wrong. That sounds more like a wager than a vacation. And you know what? The house always wins.

What are your favorite Memorial Day travel strategies? Are you still planning to take a cruise? Our comments are open.