Tropical Storm Adrian, the first storm of the 2011 hurricane season, strengthened to a hurricane off Mexico's Pacific coast, the U.S. National Hurricane Center (NHC) said Wednesday.

Adrian is located some 425 km southwest of the Mexican resort city of Acapulco, the Miami-based NHC said.

Moving in a northwest direction along Mexico's Pacific coast with sustained winds of 120 km per hour, forecasters say they don't expect the storm to make landfall.

Mexican officials have issued storm warnings for the coastal areas northwest of Acapulco.