It is well known that warm sea surface temperature (SST) anomalies are positively correlated with elevated levels of tropical cyclone activity, and much of the current literature has focused on this relationship in the North Atlantic basin. What is also known is that only a small fraction of tropical cyclones reach hurricane strength and go on to make landfall along the U.S. coastline, and that these are the events which produce the most significant human impacts. This study assesses the relationship of warm Atlantic anomalies available from the historical record with seasonal deviations from expected levels of activity, and expresses the relationship in the form of an index which can be readily adapted to “catastrophe model software”. Such an application can be used to measure the risk to property insurers and the sensitivity of that risk to climate. The integration of these results with sophisticated modeling software used to make large financial decisions will be discussed.