Sept. 10 (Bloomberg) -- Hurricane Ike started to strengthen as it entered the Gulf of Mexico and headed toward Texas, after leaving more than 170 people dead in Cuba and Haiti.

Ike's eye was 145 miles (233 kilometers) north of the western tip of Cuba and moving northwest at 8 miles per hour, the U.S. National Hurricane Center said just before 8 a.m. Miami time today. The system's sustained winds strengthened to 85 mph from 80 mph earlier today.

Ike may become a "major hurricane," the center said, a term it uses when wind speeds reach 111 mph. It is forecast to bypass New Orleans and the offshore Louisiana oil and natural gas fields and make landfall on the south-central Texas coast on Sept. 13.

There's "a significant chance that Ike will be the worst hurricane to hit Texas in 40 years," Jeff Masters, the director of meteorology at private forecaster Weather Underground Inc., said. "I am giving it a 50 percent chance of being a major hurricane at landfall."