Tropical cyclones are driven by processes that occur on various spatial and temporal scales, and studying historical patterns provides clues about how future weather scenarios may unfold. The largest signals, such as the daily heating cycle, seasonality, and El Niño, do not necessarily drive observed changes. This demonstrates the importance of examining the impacts of smaller and more long-term signals that are lesser known (i.e., new, recent Earth system changes) or have greater potential to change (unlike predictable astronomical events) both locally and globally. This study finds that ocean heat content, closely linked to atmospheric weather, has strong interannual patterns linked to El Niño but in some regions long-term changes unrelated to El Niño are impactful. The local variability of ocean heat content is strongly impacted by changing ocean dynamics and may lead to feedbacks driving more intense tropical cyclones.