 A high pressure system persisted over the south-central United States, forcing the storm to move just south of due west at 25 mph (40 km/h).On August 15, convection organized into bands, and as its winds approached hurricane strength, an eye developed within the storm.Erika turned to the west-southwest on August 16, and attained hurricane status just prior to making landfall near Boca San Rafael, Tamaulipas in northeastern Mexico, or about 40 miles (70 km) south of the United States–Mexico border.