Simplify the following text for a Grade 7 native English-speaking person.
Original: For five days after reaching its peak strength , the average radius of winds stronger than 55 km\/h ( 35 mph ) extended over 1,100 km ( 685 mi ) .
Simplified: For five days , 55 km\/h ( 35 mph ) winds extended over 1,100 km ( 685 mi ) from the center .