The complex algorithms airlines use to set prices can make getting the best deal feel like hunting for a needle in a haystack. But the travel site Cheapair.com has used its fare data to put together a calendar highlighting the best days of the week, and best overall days, to save money on flights this summer.
Here are the key points as you plan that luxurious getaway to Cape Cod/Big Sur/Oregon.
Get Data Sheet, Fortune’s technology newsletter.
Do fly on these days. The least expensive days for each month are:
- June 1st (Technically, not quite summer yet, but why not get a jump on it?)
- July 26th
- August 31st
- September 20th
Don’t fly on Sunday. It’s reliably the most expensive day of the week to fly. And bumping to Monday won’t make that much difference, saving on average only about $20.
Do fly on Tuesday or Wednesday. You’ll save an average of about $80 on your ticket on those days.
Don’t fly in July. It’s the most expensive month this summer, though if you can fly on the July 4th holiday, you’ll dodge at least a bit of the premium.
Do fly in September. Overall, it’s the cheapest month of the summer.
For more on flying, watch:
The not-too-surprising takeaway is that the best times to fly are, simply, whenever other people aren’t.
Of course, the other factor in getting a good deal is when you buy your ticket, with 54 days in advance being the exact sweet spot.
And if you’re deciding whether or not you want to travel at all this summer, remember—we’re in the midst of a solid dip in overall prices. So strap in.