If you stayed in a Hyatt hotel between August and December of last year, you should check your credit card statement for unusual charges.

The Chicago-based hotel giant said that its guests were the target of a cyberattack, and now it has unveiled the list of more than 250 hotels worldwide, including more than 100 in the U.S., that were targeted. Hyatt’s chain includes more than 600 hotels.

Hilton Worldwide and Starwood Hotels & Resorts were also struck by cyberattacks last year.

An investigation by Hyatt found unauthorized access to credit card data from cards used primarily at restaurants of the more than 250 Hyatt hotels between Aug. 13 and Dec. 8.

Hyatt said it will provide its guests who may have been a victim of the cyberattack with one year of identification protection service from CSIdentity. To sign up, Hyatt customers need to visit the website csid.com/hyatt-us.

For a list of the hotels targeted by the attack, go to hyatt.com/protectingourcustomers/hotellist.

Data reveal when to avoid air travel

By now most savvy air travelers know that the best time to book a flight is about six to eight weeks before the departure date.

But flying on certain days is going to cost more, no matter when you book.

Rick Seaney, chief executive of the website Farecompare.com, has analyzed airfare data to calculate which dates to avoid in 2016 if you want to save money:

March 17: Airfares peak as traveler’s head out for Spring Break.

May 17: Airlines increase fares for travelers flying for summer vacations.

June 10: Airfares jump again as demand grows for summer travel.

July 31: After this date, weekday fares for summer travel will begin to drop.

Aug. 22: After this date, summer airfares will begin to decline.

Nov. 23 and 27: For travelers flying for Thanksgiving, avoid the high fares on these days.