San Joaquin River - Vulcan Island UV IndexUnited StatesCASan Joaquin CountySan Joaquin River - Vulcan Island1-Day3-Day Graph Plots Open in Graphs UV Forecast NOAASan Joaquin River - Vulcan Island UV forecast issued today at 12:18 pm. Next forecast at approx. 12:18 pm. UV IndexGet WillyWeather+ to remove ads