Newcastle is a city located in the Washington region of the United States. During the most recent census, Newcastle had a population of 10,380. Newcastle is the 109th most poplulated city in the Washington region, the 3,863rd most populated city in the United States and the 20,660th most populated city in the world. Newcastle is in the America/Los Angeles timezone which is 7 hours behind UTC. Newcastle adjusts the hour with daylight savings time during the winter months.