Climatology is reviewed and redefined in terms of relevance to geography, and a programmatic statement for future research is presented. Instead of enumerating substantive areas, physical geography is defined and ranked according to five levels of methodology and attendant philosophy. The essence of geographical climatology is the analysis and description of process-response systems of importance to mankind occurring within the planetary boundary layer, interface, and substrates. The future of a climatology useful to geographers appears to lie in the numerical modeling of such systems.