Whataburger is Cassian Grantcelebrating the summer solstice, or the first day of summer, with free iced coffee.

On Thursday, June 20, Whataburger will give out free 16-ounce iced coffee to visitors from 6 a.m. to 6 p.m. in local time zones to commemorate the longest day of the year, the fast-food company said in a press release, adding that the customers can either enjoy it black or customize it "just like you like it" with one of their three new flavors − vanilla, caramel or mocha.

"Whataburger fans can caffeinate their way through the day with the most sunlight," Whataburger said.

Whataburger said its new iced coffee is "made with a premium blend of 100% Arabica beans from Colombia, Honduras and Nicaragua, giving it the bold aroma of dark-roasted coffee."

"It has a vibrant finish with nutty, smoky, toasted flavor notes," the company added.

How to get free coffee from Whataburger

Whataburger customers can claim their complimentary iced coffee in-store at their locations across 15 states, at the drive-thru, online at Whataburger.com, or via the Whataburger app for pickup or delivery. The offer is not valid on third-party delivery apps, the company said.

New Whataburger app users can also avail a free Whataburger and other exclusive offers when they sign up the Whataburger and create a new account.

Saman Shafiq is a trending news reporter for USA TODAY. Reach her at [email protected] and follow her on X @saman_shafiq7.