Jackson said after the 2016 season, when the Browns went 1-15, that he would jump into Lake Erie if they finished 1-15 again in 2017.
They did not finish 1-15; they were worse, becoming the second team in history to go 0-16.
The team announced on its website on Monday that Jackson will take the plunge on June 1. Jackson will make the jump for the symbolic cleansing of the franchise and for charity.
The coach will donate $100 to his foundation, which combats human trafficking across Northeast Ohio, for every Browns employee who joins him in jumping into Lake Erie.
Jackson had a stent placed in his heart in 2014, and his doctors did not allow him to jump into the frigid water immediately after the 2017 season ended, according to the Cleveland Plain Dealer. The water is warmer now.
"I don't like it," Jackson said in late December. "I don't like to do it for the reason I am having to do it, but I have to make do on my word. I just think that is what you do. I do get that. I made a statement. I have to back it up. That is the type of person I am, so that is what we have to do."