Hello: You can use the "oacres" function to perform Cressman objective analysis on the station data: http://www.iges.org/grads/gadoc/gradfuncoacres.html And this page explains how to deal with the station data: http://www.iges.org/grads/gadoc/aboutstationdata.html Regards -- GrADS Palette - http://cypresslin.web.fc2.com/Projects/ENG-GrADSPalette.html