Puerto Vallarta, Guadalajara, and the rest of Jalisco State fall into Central Standard Time (the same as Mexico City). Nayarit and other parts of the northwest coast are on Mountain Standard Time.
The fact that the state of Nayarit (including Nuevo Vallarta and the rest of the Riviera Nayarit) are in a different time zone from Puerto Vallarta and points east and south leads to confusion. And to add to this confusion, Mexico does observe daylight saving time, but not on the same schedule as the United States.
Businesses in Nuevo Vallarta and most tourism-related businesses in Bucerías, La Cruz de Huanacaxtle, and Punta de Mita run on Jalisco time. Since tourism in these towns has traditionally been linked to that of Puerto Vallarta, hotels in the two areas almost always run on Jalisco time to avoid having their clients miss planes when returning home. However, as Nayarit State exerts itself as a destination in its own right with development of the Riviera Nayarit, this is no longer a given. When asking the time, checking hours of operation, or making dinner reservations, double-check whether the place runs on hora de Jalisco (Jalisco time) or hora de Nayarit.