Which day is best to avoid kids on the plane? Hopper data gives the answer.

People of all ages have to travel, but some adults can be a little grumpy about seeing kids on planes. If you’re one of those flyers who would rather be at 30,000 feet only with people who are legally old enough to vote, you might want to consider flying on a Sunday in September.

Data from Hopper, the online travel booking platform, shows that Sundays and the fall are the least popular days for kids to take to the skies.

Hopper’s data uses 12 as the cutoff point for what counts as a child traveler, so some voting-ineligible flyers may still sneak through. According to the Hopper research, 4.6% of bookings on Sundays include children, compared to 6.6% on Saturdays.

If weekend travel isn’t your thing, Thursday or Friday flights are your next best bet, with just 4.9% and 5.0% of bookings including children on those days, respectively.

Mid-week travel is the most popular for kids after Saturdays, with 6.1% of bookings including kids on Tuesdays and 6% on Wednesdays.

Not surprisingly, summer is a popular time for kids to travel, with June, July and August seeing the highest share of bookings with children for the year, followed by winter holidays and the period around spring break.

"These peak times align with when kids are out of school," Hayley Berg, lead economist at Hopper told USA TODAY in a statement.

And where to go if you want to avoid kids? According to Hopper, children are least likely to be on flights to Las Vegas and most likely to be on flights to Orlando.

"Our top 10 most popular routes with kids under the age of 12 are to Orlando. Trips to Orlando also over index for parents flying with infants under 2 years old," Berg said.

Travel on Sunday if you want to have the best chance of a kid-free flight.
Travel on Sunday if you want to have the best chance of a kid-free flight.

Can families sit together for free on planes?

The Biden Administration has been pushing airlines to let families select seats together on flights for no extra charge. While there’s no law to require carriers to do this, some have voluntarily adopted it as a policy. According to the Department of Transportation, Alaska Airlines, American Airlines, Frontier Airlines and JetBlue guarantee adjacent seats for children 13 or under and an accompanying adult at no additional cost for all fare types.

If you're traveling with children, Berg especially recommends insuring your trip.

"If you're booking an upcoming trip with young children, we recommend adding trip protection so you're not stuck at the airport due to a delay or cancellation," she said.

This article originally appeared on USA TODAY: When to travel if you don't want kids on your flight