Coastal flooding, often seen as a chaotic and unpredictable event, may actually follow a highly predictable pattern based on daily tides, according to a recent study published in Nature Communications. The research, led by Ivan Haigh from the University of Central Florida and a team of international scientists, reveals that coastal floods tend to occur at specific times of day, influenced by the natural rise and fall of ocean tides. While previous studies have examined the seasonal timing of floods, this is the first to demonstrate that the daily timing of impactful floods is consistent across different regions. The researchers analyzed tide gauge data and historical flood records from the United States and the United Kingdom to identify patterns in flood timing. For example, in Boston, floods are most common around noon and midnight, while in Southern California, they tend to occur in the morning. In Florida, the timing of floods varies along the coast due to regional differences in tides. Along the Atlantic Coast and the Florida Keys, the timing of floods is somewhat predictable, but along the Gulf Coast, the predictability is lower. Tides play a central role in determining when floods occur. According to Haigh, the daily rise and fall of tides largely dictate whether a storm surge or high water level will exceed flood thresholds. "Even storm-driven flooding often inherits the timing of the tides," he explains. This pattern is not limited to areas with semidiurnal tides, which have two high and two low tides each day. It also applies to regions with diurnal tides, which have one high and one low tide per day, due to the way different tidal signals interact. As global sea levels continue to rise, coastal flooding is happening more frequently, even without the presence of storms. Haigh emphasizes that the timing of floods can greatly affect their impact. A flood during a morning commute or business hours can cause more disruption than one that happens at night. Understanding these patterns can improve flood forecasting, emergency planning, and infrastructure management. As sea levels rise, knowing when high tides will occur becomes increasingly important for predicting and preparing for floods. "Higher mean sea levels mean that even a small weather event or a high tide can cause flooding," Haigh says. "Identifying these critical tidal windows could become a key element in coastal flood preparedness."