The TopoWx ('Topography Weather') dataset contains historical 30-arcsec resolution (~800-m) interpolations of daily minimum and maximum topoclimatic air temperature for the conterminous U.S. Using both DEM-based variables and MODIS land skin temperature as predictors of air temperature, interpolation procedures include moving window regression kriging and geographically weighted regression. To avoid artificial climate trends, all input station data are homogenized using the GHCN/USHCN Pairwise Homogenization Algorithm (http://www.ncdc.noaa.gov/oa/climate/research/ushcn/#phas). The interpolation model is open source and information on obtaining model code can be found at http://www.ntsg.umt.edu/project/TopoWx. The following data are available in this archive: 1948-2014 daily minimum and maximum temperature, and 1981-2010 monthly normals for minimum and maximum temperature with corresponding uncertainty (kriging prediction error). Ongoing annual updates will regenerate the entire dataset incorporating both new observations and model enhancements. This will result in a continuously improved dataset. However, different versions of TopoWx will be incompatible. For instance, data from the original 1948-2012 version should not be mixed with data from the new 1948-2014 version.