Potomac River - Mattawoman Creek Entrance UV IndexUnited StatesMDCharles CountyPotomac River - Mattawoman Creek Entrance1-Day3-Day Graph Plots Open in Graphs UV Forecast NOAAPotomac River - Mattawoman Creek Entrance UV forecast issued today at 2:17 pm. Next forecast at approx. 2:17 pm.Get WillyWeather+ to remove ads