Earlier study with principal component analysis has shown that the diurnal cycle of land surface temperature can be approximated with root-mean-square accuracy of about 1-2°C by two empirical orthogonal functions, which characterize the mean temperature level and the diurnal temperature range (DTR), respectively. The current study focuses on DTR, whose properties on the global scale have not been sufficiently investigated. Long-term time series of monthly mean day- and nighttime surface temperatures and DTR have been derived from two climatological data sets aimed primarily at the characterization of atmospheric processes from operational environmental satellites. The NOAA/NESDIS Pathfinder Atmosphere (PATMOS) data set includes daytime and nighttime clear-sky radiance products from 1981 through 2000. Clear sky radiances from the International Satellite Cloud Climatology Project (ISCCP) D-2 product are available for the 1983-1993 period. The three-hourly ISCCP data have been interpolated into hourly resolution by a cubic spline. Coincident PATMOS and ISCCP data have been compared for consistency. ISCCP data have been used as a training data set to derive relationships between daytime and nighttime PATMOS temperatures and DTR, along with higher-resolution information on vegetation cover from the NOAA/NESDIS Global Vegetation Index (GVI) data set. These relationships were used to derive a global monthly climatology of DTR, including the filling of the gap in the global maps of ISCCP-derived DTR over Asia and north of 60°N. Time series of DTR have been extended to the 20-year period of PATMOS. Early results confirm on a global scale the occurrence of a DTR maximum, but also a significant interannual variability, at mid-latitudes during the period between snow retreat and springtime green-up. The DTR monthly data sets derived will be useful for many other climate- and remote sensing related applications. Among them are validation of DTR produced by numerical climate models, monitoring of DTR in long-term climate change studies, and mapping thermal inertia on a global scale.