Miami ? Tropical Storm Delta neared hurricane strength Thursday in the central Atlantic, continuing a record-breaking hurricane season.

The 25th named storm of the season formed Wednesday and poses a threat only to shipping, according to the National Hurricane Center in Miami. It was not headed for the United States.

Delta was centered about 1,215 miles southwest of the Azores. At 9 p.m., Delta’s top sustained winds were near 70 mph and the storm was expected to intensify a bit. It would become the 14th hurricane of the season if those winds reach 74 mph.

The six-month Atlantic hurricane season officially ends Wednesday.