(CNN) -- Hurricane Ida weakened to a Category 1 storm as it churned across the Gulf of Mexico early Monday, forecasters said.
Its maximum sustained winds are 90 mph (145 km/hr), with higher gusts, the National Hurricane Center said.
Additional weakening is forecast for the next 24 hours, but Ida is still expected to be a hurricane when it approaches the Gulf Coast on Monday or early Tuesday, the center said.
A hurricane warning is in effect from Pascagoula, Mississippi, eastward to Indian Pass, Florida, forecasters said. The warning means hurricane conditions are expected within 24 hours.
Measures to protect life and property should be undertaken, forecasters said.
Ida is moving toward the north-northwest near 16 mph (26 km/hr). It is expected to bring a total of 8 inches of rain across the central and eastern Gulf Coast.
The hurricane prompted a state of emergency in Louisiana when it moved into the southern Gulf of Mexico on Sunday.
Ida "threatens the safety and security of those citizens" along the state's southeast coastline, Louisiana Gov. Bobby Jindal said. The declaration gives the state director of emergency preparedness the authority to prepare for the hurricane.
In Alabama's Baldwin County, officials urged residents living in mobile homes, coastal communities or low-lying, flood-prone areas to voluntarily evacuate. The county is also under a local state of emergency and opened a shelter, the county commission said.
Florida's Division of Emergency Management asked residents to have disaster plans in place.
"Whether Ida maintains a storm or loses tropical characteristics, the Florida Gulf Coast region has the potential to see several inches of rain, strong winds, isolated tornadoes, and dangerous surf and coastal flooding ," the office said in a statement.
Ida is the Atlantic region's ninth named storm. The Atlantic hurricane season ends November 30.