California Coast Sees Record High Water Levels

Last week, many places along the California coast had very high water levels. This happened because of a strong El Niño this year. Some places saw the highest water levels ever recorded, with data going back over one hundred years.

From October 24 to 30, 2026, water levels were measured above the usual high tide level, called Mean Higher High Water. Four locations had their highest water levels ever. Other places had water levels in their top ten highest.

The high water levels happened because of several reasons. First, the moon and sun’s positions caused higher tides than usual. A special tide called a perigean spring tide occurred when the moon was full and closest to Earth.

Second, El Niño caused large ocean waves called Kelvin waves. These waves moved warm water toward the California coast, raising the sea level by about six to twelve inches over several weeks.

Third, a marine heatwave warmed the ocean water. Warm water takes up more space than cold water, so the sea level rose even more. These factors together caused flooding that affected roads, homes, and businesses.

If the El Niño continued and the moon was full and close to Earth again, water levels would rise even more. NOAA expects more high tides and possible floods in late November and December 2026. People can check NOAA’s tools to learn about flood risks and water levels.