Temecula is a city in southwestern Riverside County, California, United States. The city had a population of 110,003 as of the 2020 census a…Temecula is a city in southwestern Riverside County, California, United States. The city had a population of 110,003 as of the 2020 census and was incorporated on December 1, 1989. The city is a tourist and resort destination, with the Temecula Valley Wine Country, Old Town Temecula, the Temecula Valley Balloon & Wine Festival, the Temecula Valley International Film Festival, championship golf courses, and resort accommodations contributing to the city's economic profile.