High tide and storm surges can contribute to rapid rises in sea level along the shore (rise in sea water caused by the wind of a storm and which can flood coastal land). Considering that high tide is predictable, there are seldom any issues. Although storms aren’t always necessary to cause coastal flooding, global warming has led to a rise in sea level and other consequences that increase the number of times such flooding occurs.

In the United States, three locations—one each on the Atlantic and Pacific coasts—experienced unprecedented flooding due to high tides in 2013. The National Oceanic and Atmospheric Administration (NOAA) predicts that this tendency will continue through 2023 and beyond unless such flood prevention measures are enhanced.

From May 2021 to April 2022, NOAA’s 97 tide gauge stations throughout the United States’ coastline recorded fluctuating high-tide flooding trends.

Various factors, including the gradual but steady rising of sea levels over the last few decades, are contributing to the increasing frequency with which high tides cause floods. Water starts to overflow onto roadways and rush out of storm drains when tides rise 50 to 60 cm over the normal high tide for that time of day.

The destructive flooding that used to occur exclusively during storms will now occur more often, such as during a full moon or with a favorable shift in prevailing winds or currents, as sea levels continue to rise.