Hurricane activity has been higher since 1995 than in the 1970s and 1980s. This rise in activity has been linked to a warming Atlantic. In this study, we consider variability of the volume of water warmer than 26.5 ºC, taken as the temperature threshold crucial to hurricane development, through the Water Mass Transformation framework. The volume of water transformed by surface heat fluxes to temperatures of 26.5 ºC is calculated, and compared with the year to year changes in the volume of water of this temperature. Variability of transformed volume is largely due to latent heat flux processes, associated in turn with anomalies in cloud fraction and surface winds. In some years, there is correspondence between transformed and observed volume anomalies, but in other years, alternative processes must drive observed volume anomalies. Coordinated physical mechanisms are thus responsible for anomalous ocean heat, providing fuel for larger numbers of intense hurricanes.