King tides: dates, heights, and why they happen

King tide is the popular name for the highest tides of the year. NOAA calls them perigean spring tides. They happen when a new or full moon lines up with perigee, the point where the Moon's orbit brings it closest to Earth. There is no official cutoff for how close the match has to be, so the names and dates you see quoted vary a little from one source to another.

This page counts a new or full moon when perigee falls within 36 hours of it. By that rule the next window is the full moon on November 24, 2026, with perigee 33 hours after it. The twelve months from today hold 6 windows: Nov 24, Dec 23, Jan 22, Jul 3, Aug 2, and Aug 31.

King tide dates for the next 12 months

Each window below lists the highest predicted high water at six stations, one for each coast region, from one day before the new or full moon to four days after it. Heights are feet above MLLW, the zero line on NOAA tide charts (see tide datums explained). The smaller number under each height compares the peak with that station's average high water over the same twelve months. Moon dates are in Eastern time, and each station shows its own local time.

How much the water rises follows the tidal range. The bump is largest where the daily range is large, as at Boston and Seattle, and smallest on the Gulf Coast, where the range is small and water levels follow the weather more than the Moon. On the Pacific coast the winter windows usually give the highest numbers. Every station page lists its own tides, so open the one nearest you from tide times by location.

Why king tides happen

Every new and full moon brings spring tides: Sun, Earth, and Moon line up, their pulls add, and the tidal range grows. The Moon's orbit is an oval. Once a month it carries the Moon closest to Earth, at perigee, and about two weeks later farthest away. The Moon's pull grows quickly as it gets closer, so a perigee that lands on a new or full moon stacks one boost on top of another. That is a king tide. The two-week rhythm underneath is covered in our guide to spring vs neap tides.

Perigee comes every 27.5 days and a new or full moon every 14.8 days, so the two line up for two or three months in a row and then drift apart for about half a year. Season adds to it. Earth is closest to the Sun in early January, which lifts the solar part of the tide a little, and on many coasts the water itself sits higher in fall. Where those line up with a perigean spring tide, you get the biggest water of the year.

Why king tides matter

Sunny day flooding. Because king tides are the highest water of the year, they preview where sea level rise will reach first. Low streets, docks, boat ramps, and storm drains that stay dry the rest of the year can flood around the peak with no storm in sight, and coastal agencies run king tide photo projects for that reason. If you live or park near the water, check the dates before the water finds your floor mats.

On the water. Bigger tides move more water, so currents run harder than usual, flats and marsh edges that are dry most of the year can hold fish, and ramps and docks sit at unusual heights. The strongest flow does not always arrive with the highest water; tide vs current explains the gap.

The low side. Every extreme high is followed by an extreme low on the same cycle. King tide lows uncover rocks, flats, and tidepools that stay underwater most of the year, which makes them good days for tidepooling and clamming. See minus tides, clamming, and tidepooling for how to plan the walk.

Staying safe

King tides deserve respect. The water rises and falls through a bigger range in the same hours, so currents run stronger than usual and the flood can cut off a beach or sandbar faster than you expect. Give low-lying paths extra margin, watch the clock near the turn, and remember that wind and low pressure can push the real water level above the prediction.

How these dates and heights are calculated

Moon phase and perigee come from the same astronomy code the Slackwater app uses for moon phase and solunar times. Heights come from NOAA's harmonic constants for each station, run through the predictor behind every station page. Nothing on this page is typed in by hand. The list is regenerated each time the site is rebuilt, which happens daily, so the twelve months always start today.

These are predictions from astronomy alone. Wind, air pressure, and storm surge can lift the real water above them, and a long offshore wind can hold it below. We compare the heights with NOAA's own published predictions: for the stations above they agree to within a few tenths of a foot, and the times to within a few minutes. On the Gulf Coast the day's two highs are often almost the same height, so the highest one can fall on a different day depending on the source. A new or full moon a little more than 36 hours from perigee still raises the tide, just by less, and is not listed.

Find yours in Slackwater

The Slackwater app computes the full tide curve for your station on your device from NOAA harmonic data, so you can scroll ahead to any of these dates and read the height for your own spot, even with no signal. On the web, tide times by location has a page for each of 781 stations.