MIAMI (AP) — A hurricane watch was in effect early Saturday for coastal Texas as Tropical Storm Beta gains strength in the Gulf of Mexico during an exceptionally busy Atlantic hurricane season.

Beta was 310 miles (500 kilometers) east of the mouth of the Rio Grande with maximum sustained winds at 60 mph (95 kph), the U.S. National Hurricane Center said in an advisory. Forecasters said the storm was expected to become a hurricane on Sunday.