In order to characterize the solar UV radiation reaching the Earth's surface it is monitored from space by means of (i) the clear-sky UV index at local solar noon, which is most relevant for operational UV forecasting, and (ii) the daily UV dose including cloud shielding effects, which is most relevant for long-term UV monitoring and assessments of health risks and biological UV effects. Optimal space-based surface UV monitoring combines information from platforms in different orbits. Space-based total ozone column products from polar orbiting platforms can be used adequately for UV monitoring because the diurnal variability in the total ozone column is limited. However, cloud cover and cloud optical thickness typically vary significantly on time scales of minutes to hours, especially over land in relation to convective activity. Because diurnal variations in cloud amount and cloud optical thickness impact dramatically on the daily-integrated UV radiation levels transmitted to the Earth's surface, the time variations in (key) cloud parameters over the day need to be captured by observations. Sampling of the diurnal variations in clouds is most efficiently done from geostationary platforms. Here we demonstrate examples of calculations of the clear-sky UV index and the UV daily dose for erythema over Europe based on assimilated total ozone column data derived from observations by GOME aboard ERS-2 and its successor SCIAMACHY aboard ENVISAT, in combination with cloud information retrieved from MVIRI aboard Meteosat-7 and its successor SEVIRI aboard MSG (Meteosat-8). Some first validations with ground-based surface spectral UV data are presented.