What is coastal?

Historical definitions of what determines whether one lives in a coastal area or not have varied over time, from using coastal watershed boundaries, shoreline-adjacent coastal counties, and even counties impacted by flooding from coastal storms. The definition one chooses can have major implications, including a simple count of coastal population and the influence of local or state coastal policies. There is, however, one aspect of defining what is “coastal” that has often been overlooked; using atmospheric long-term climate variables to define the inland extent of the coastal zone. This definition, which incorporates temperature, precipitation, wind speed, and relative humidity, is furthermore scalable and globally applicable - even in the face of shifting shorelines. The resulting definition, “coastal climate” or “climatology of the coast”, will help coastal resource managers make better-informed decisions on a wide range of climatologically-influenced issues. The presentation will outline the development of this new definition of the coastal zone, and specifics will be presented on the incorporation of each atmospheric and climatic variable using in situ weather station data. In addition, a new U.S. national map depicting the climatic definition of the coastal zone will be shown.