The purpose of this study was to identify the ex-ante determinants of disaster preparedness in daily life, termed everyday awareness of disaster preparedness, which influence evacuation behavior during heavy rainfall events. A panel survey was conducted among residents of flood- and landslide-prone areas in Ehime Prefecture before and after heavy rainfall. A pre-survey explored a wide range of variables related to participants’ everyday awareness of disaster preparedness prior to heavy rains, followed by a post-survey that examined their actual evacuation behavior when evacuation warnings were issued during subsequent heavy rains. By analyzing the survey data, we identified prior variables related to disaster preparedness that were associated with evacuation choice. The participants had a high level of disaster preparedness, including evacuation intentions, but many of them did not actually evacuate even when evacuation warnings were issued due to heavy rains. Furthermore, only prior contemplation of evacuation criteria (associated with the commitment to evacuate) was directly related to evacuation behavior. Finally, mediation analysis indicated that prior contemplation mediated the relationship between evacuation intentions and actual evacuation. The implications of these findings for education and communications to reduce disaster risk are discussed.