 That day, Diane reached its lowest pressure of , and peak winds of 105 mph (170 km/h); originally the hurricane was analyzed to reach peak winds of 120 mph (195 km/h), although the large size and slow forward speed suggested the lower winds.It maintained its peak winds for about 12 hours, after which it weakened due to cooler air in the region.By August 15, the eye had become poorly defined, and winds steadily weakened.