Rancho Cucamonga (ˌræntʃoʊ_kuːkəˈmʌŋɡə ) is a city located just south of the foothills of the San Gabriel Mountains and Angeles National Forest in San Bernardino County, California, United States. About east of Downtown Los Angeles, Rancho Cucamonga is the 28th most populous city in California. The city's seal, which centers on a cluster of grapes, alludes to the city's agricultural history including wine-making. The city's proximity to major transportation hubs, airports, and highways has attracted the business of several large corporations, including Coca-Cola, Frito-Lay, Big Lots, Mercury Insurance Group, Southern California Edison, and Amphastar Pharmaceuticals.
The city had a population of 174,453 according to the 2020 United States Census. The city experiences an average of 287 sunny days per year, compared to a national average of 205 days. Its climate is classified as warm Mediterranean, or Csa, under the Köppen climate classification system.