Wine is the most differentiated of all farm products, with much of the differentiation based on the location of production. In this paper, we estimate the effects of climate and vintage weather on California's varietal wine quality and prices. Our analysis is based on a sample of premium wines rated by Wine Spectator magazine between 1994 and 2022 and a comparable sample of secondary market auction prices from K&L Wine Merchants, each matched to spatially detailed weather data from PRISM. We find that extreme temperatures, particularly extremely hot temperatures, caused prices to decline. Absent additional adaptation, climate change will harm wine quality and disrupt quality signals from geographical indications in California's premier wine regions.