The US National Hurricane Center in Miami said Vance was generating maximum sustained winds of 110 mph (175 kph) Monday afternoon. It was centered about 465 miles (745 kilometres) west-southwest of Manzanillo and moving to the north at 12 mph (19 kph).
Forecasters said the Category 2-strength storm was expected to make a turn toward the north-northeast over the next day or so, but would start to weaken later Monday.
The hurricane center warned the storm could generate dangerous surf and rip-current conditions along the coasts of southwestern Mexico and Baja California Sur between last night and today. Northwestern states of Sinaloa, Nayarit and Durango could see heavy rain, including downpours capable of causing flash floods and mudslides.