Nik Wallenda walks on a tightrope in the rain during training for his walk over Niagara Falls Friday. David Duprey / AP

Nik Wallenda trains for his walk over Niagara Falls on a 2-inch wire. David Duprey / AP

Nik Wallenda trains in the rain for his walk over Niagara Falls. David Duprey / AP

Nik Wallenda performs a walk on a tightrope in the rain during training for his walk over Niagara Falls. David Duprey / AP