Recent research has revealed that the causes of heavy rainfall leading to large‐scale sediment‐related disasters are the formation of warm‐moisture current convergence zones caused by isolated ridges or narrow topographies (hereinafter referred to as ‘sediment‐related disaster‐inducing convergence zones’). Analyses also demonstrate that these convergence zones possess both universal traits and regional variations driven by their specific topography. This study focused on the Koyaura area of Saka Town Hiroshima Prefecture, where five sediment‐related disasters have occurred since 1907. Using weather maps and ERA5 (ECMWF Reanalysis v5) reanalysis data, we identified the location of the front and typhoon at the time of the disaster, as well as the wind direction and speed of the warm, moist air current. Furthermore, using a similar method, we identified recent rainfall events that exceeded a certain rainfall threshold but did not cause sediment‐related disasters. As a result, we analyzed that heavy rainfall that caused sediment‐related disasters occurred when the front was located from the Koyaura area to Shimane Prefecture, and when the typhoon was located in Hiroshima City. And the wind direction was “southwesterly” in the both case. It is inferred that the convergence of Etajima extends to the Koyaura area. These two factors can be known by residents and disaster prevention personnel using the Japan Meteorological Agency’s forecast weather charts and 850hPa pressure surface weather charts. The terrain that causes convergence does not change. Based on the above, it is believed that by understanding the past locations of heavy rain fronts and typhoons, as well as the locations and wind directions of future fronts and typhoons, it will be possible to improve risk management against large‐scale sediment‐related disasters.