Weather Words: King Tides

Like a king towering over his kingdom, king tides bring the ocean to its highest levels, temporarily reshaping coastlines. These naturally occurring tides happen when the Sun, Moon, and Earth align just right, intensifying the gravitational pull on the ocean and creating water levels that rise higher than usual.

Unlike storm surges or tsunamis, king tides are predictable and occur several times a year, typically during full or new moons when the Moon is closest to Earth. While they don’t result from storms, when a storm happens to occur during a king tide, their impacts can be even more significant. Coastal communities are especially vulnerable to king tides, where they can lead to flooding of streets, docks, and even homes. This type of flooding is sometimes called “sunny day flooding” because it can happen without a storm in sight.

In California, king tides are particularly noticeable in places like San Francisco Bay and low-lying coastal areas, where they can exacerbate erosion and provide a glimpse into the future of rising sea levels. On the East Coast, Miami is also susceptible to king tides, as water rises into the streets, creating travel issues in and around South Beach.

As climate change causes rising seas, king tides are only expected to worsen. Scientists and environmental groups often encourage residents to document these extreme tides, using them as a real-world preview of how climate change may reshape coastlines in the years ahead.

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.