Now a category 4 storm with 230km/hr winds, Rita is threatening to hit up to 16% of the country’s refining capacity, according to various reports.

In comparison, Hurricane Katrina forced the shutdown of nine refineries, four of which still remain offline and represent about 5% of US output.

Ports in Houston and Port Arthur are currently in the storm’s path, which could disrupt about 10 to 15% of US oil imports, said the API.

This latest hurricane has forced the evacuation of oil rigs and platforms across most of the central and western Gulf of Mexico. Earlier this morning, the federal Minerals Management Service said that 92% of offshore oil production was closed. The Gulf accounts for more than a fifth of US domestic oil production.

The storm is about 465km south-east of Louisiana and 565km south-east of Galveston, Texas, according to the National Hurricane Centre at 9am AEST this morning.

Meanwhile, environmentalists in the US have warned of the possibility of a toxic spill from the 87 industrial plants and storage installations in Rita’s sight.

The US mainland has not been hit by two category 4 storms in the same year for 90 years. Now it looks likely Rita will follow Katrina’s lead in less than one month.