As of 7 pm CST, Nora was located about 48 km south southwest of Puerto Vallarta, Mexico, packing maximum sustained winds of 129 kph.
From the western coast of Mexico, the hurricane is then projected to approach and move into the Gulf of California on Sunday and Monday.
Besides, Hurricane Ida intensified over warm Gulf of Mexico waters on Saturday, prompting tens of thousands to flee coastal areas, while the US president Joe Biden pledged aid to help states quickly recover once the storm has passed.
Forecasters said Ida could make a US landfall on Sunday night as an "extremely dangerous" Category 4 storm on the five-step Saffir-Simpson scale, generating winds of 225 kph, heavy downpours and a tidal surge that could plunge much of the Louisiana shoreline under several feet of water.
On Saturday evening Ida was about 320 km southeast of the mouth of the Mississippi River, packing top winds of 169 kph and aiming for the Louisiana coast, the National Hurricane Center said.
"We're concerned about explosive development shortly before it makes landfall," said Jim Foerster, chief meteorologist at DTN, which provides weather advice to oil and transportation companies.
Flooding from Ida's storm surge - high water driven by the hurricane's winds - could reach between 3 and 4.5 metres around the mouth of the Mississippi River, with lower levels extending east along the adjacent coastlines of Mississippi and Alabama, the NHC said.
Officials ordered widespread evacuations of low-lying and coastal areas, jamming highways and leading some gasoline stations to run dry as residents and vacationers fled the seashore.