As the art of forecasting the UV Index moves into its second decade, some issues affecting the creation of a valid UV Index forecast have been solved, yet others remain. The forecast of the UV Index is really the combination of multiple forecasts of ozone, clouds, and (in the future) aerosols. Ozone forecasts have improved significantly due to the assimilation of ozone into global numerical weather prediction models. The affects of aerosols on UV radiation are increasingly better understood. Parameterization of other factors affecting the UV radiation reaching the surface (albedo and elevation) have been increasingly studied and their affects better known. Clouds remain to be the primary source of error in UV Index forecasts. Each of these topics will be discussed with their impacts on the resulting UV Index forecast.