Tropical Storm Erin formed Monday and is expected to become a major hurricane as it moves across the Atlantic Ocean, according to the National Hurricane Center, though the potential risks to the U.S. remain unclear.

The National Hurricane Center issued its first advisory on the fifth-named storm of the Atlantic hurricane season at 11 a.m., warning Erin could become a hurricane by Wednesday, Aug. 13 and a major hurricane by Saturday, Aug. 16, as it moves quickly west across the Atlantic.

Historically the first major hurricane of North American hurricane season doesn’t arrive until the beginning of September