At 0300 GMT (0830 IST) the eye of Amanda was far from land, some 1,070 kilometres southwest of Manzanillo, Mexico and heading further out to sea in a west-northwest direction, the NHC said.
Amanda was packing sustained winds of 185 kilometres per hour, making it a Category Three storm on the five level Saffir-Simpson scale.
"Some additional strengthening is expected during the next day or so, with gradual weakening forecast to begin on Monday," the NHC said.
The storm is moving at near five kilometres an hour and is forecast to turn towards the north-northwest today.