Riverside California Riverside County is southeast of Los Angeles. In the viticultural world it is best known for being home to the Temecula Valley. Vineyards & Wineries: Alex's Red Barn Winery Callaway Vineyard & Winery Inn at Churon Winery Maurice Car'rie Winery Providence Family Winery Thornton Winery Wiens Cellars AVAs in Riverside County: Temecula Valley