Irene was a TS not a hurricane

Irene was a tropical storm, not a hurricane when it made landfall in the US. It was a hurricane in the Caribbean, through the Bahamas (Cat 3, then 2, then 1) and as it approached the coast of the US. But it was not a hurricane when it hit land. It was Tropical Storm Irene that crossed the coast of North Caroline, New Jersey and New York.

A hurricane has sustained winds of 64 knots, which is 74 mph.

WattsUpWithThat has time graphs of the winds at places the eye passed over. In North Carolina it was a strong tropical storm. In New York it was barely a TS.