Does the full moon cause high tides? Spring and king tides explained.

The full moon does not cause high tide by itself: most coasts see two high tides a day at every phase of the moon. What the full moon does, exactly like the new moon, is line up the sun, Earth and moon so that their tidal pulls add together. The result is a spring tide, with high water a little higher and low water a little lower than average.

Stand on a tidal beach for a few hours and you can watch it happen. Water that lapped at the sea wall slides back across wet sand, then returns as steadily as it left: the gravity of another world, visible from the shore. This article covers how the moon lifts the oceans, why full and new moons bring spring tides, what a king tide really is, where the biggest tides on Earth occur, and why the same force does nothing measurable to the water in your body.

How does the moon lift the oceans?

The moon pulls on the whole Earth, but not equally everywhere. The side of the planet facing the moon is about 12,700 km closer to it than the far side, and gravity weakens with distance. That difference in pull, not the pull itself, is what makes tides.

On the side facing the moon, the ocean is pulled slightly harder than the solid Earth beneath it and bulges toward the moon. On the far side the opposite happens: the solid Earth is pulled toward the moon more strongly than the distant water, which is left behind as a second bulge. So there are two bulges, on opposite sides of the planet.

Earth turns underneath those bulges. Because the moon also moves along its orbit in the same direction, it takes the Earth an extra 50 minutes to catch up with it, which is why NOAA describes a tidal day of 24 hours and 50 minutes. Most coasts pass through both bulges in that time, giving two high tides and two low tides, each arriving roughly 50 minutes later than the day before.

Not every coast follows that rhythm neatly. Continents block and redirect the bulges, so NOAA distinguishes three patterns: two roughly equal highs a day (typical of the US East Coast), two unequal highs (the US West Coast), and just one high and one low a day (parts of the Gulf of Mexico).

What are spring tides and neap tides?

The sun raises tides too. It is vastly more massive than the moon, but tide-raising force falls with the cube of distance, and the sun is almost 400 times farther away. NOAA puts the sun’s tide-generating force at about half that of the moon. Enough to matter, not enough to lead.

What the sun adds depends on where it stands relative to the moon. At full moon, Earth sits between the sun and the moon. At new moon, the moon sits between Earth and the sun. Either way the three bodies are in a line, the solar and lunar bulges stack, and the tidal range grows: high tides a little higher, low tides a little lower. Those are spring tides. The name has nothing to do with the season. It comes from the idea of the tide springing forth, and it happens twice every lunar month, all year round.

About a week later, at first or last quarter, the sun and moon pull at right angles. The sun’s bulge partly fills the moon’s troughs, and the range shrinks to its monthly minimum. These are neap tides, with low tides that are not very low and high tides that are not very high.

There is one practical wrinkle. The biggest tides rarely arrive at the exact moment of full or new moon. At many places they come a day or two later, a delay oceanographers call the age of the tide, because the oceans take time to respond. If you are timing a beach walk or a fishing trip, check a local tide table rather than the moon’s phase alone.

What is a king tide, and why do some full moons flood streets?

The moon’s orbit is an ellipse, and its distance from Earth changes by tens of thousands of kilometers over a month. When the moon is at its closest point, called perigee, its tide-raising force is stronger than usual. When a new or full moon falls close to perigee, the two effects combine into a perigean spring tide. According to NOAA, this lineup happens often six to eight times a year.

King tide is the popular name for these exceptionally high tides. It is not a scientific term, but it has stuck. NOAA notes that high tides during a perigean spring tide are commonly more than a foot higher than during spring tides when the moon is far away, and near Anchorage, Alaska, the difference can exceed three feet.

You can put numbers on the moon’s side of it. Tidal force scales with the inverse cube of distance, so at 357,635 km, the distance of the January 2027 supermoon, the moon’s tide-raising force is roughly a quarter stronger than at its average distance of 384,400 km. At the farthest full moon of 2027 it is about 15 percent weaker.

The full moon does not raise the tide by itself. It puts the sun and moon in one line, and when the moon is also at its closest, the ocean climbs a little higher up the shore.

On its own, a king tide rarely causes more than nuisance flooding. In low-lying places such as Miami, seawater can spill into streets without any rain or storm, which is why it is called sunny-day flooding. Serious flooding comes when a spring tide coincides with a storm. When Storm Eleanor hit Europe in January 2018, extra-high tides and violent winds arrived together, and coasts paid the price. The moon sets the ceiling of the tide; the weather decides how far above it the water climbs.

Where are the biggest tides on Earth?

The moon’s pull is the same everywhere, but the shape of the coast decides what the water does with it. Funnel-shaped bays squeeze the incoming tide, and basins whose natural sloshing rhythm matches the tides amplify it. Some of the world’s standout places:

• Bay of Fundy, Canada. The highest tides in the world. NOAA places the record at Burntcoat Head in Nova Scotia, and the difference between low and high water in the bay can reach about 16 meters.
• Cook Inlet, Alaska. The largest tides in the United States, with ranges around Anchorage averaging about 30 feet (9 meters).
• Severn Estuary, UK. One of the largest tidal ranges anywhere, about 15 meters, and home to the Severn bore, a wave that runs upriver on the biggest spring tides.
• King Sound, Western Australia. The largest tides in Australia, with a maximum range of 11.8 meters at Derby.
• Hooghly River, India. Below Kolkata the incoming tide has long been known to arrive as a tidal bore, historically recorded at more than two meters high.
• Mediterranean Sea. The opposite extreme: tides of only a few centimeters on average, because the sea connects to the ocean through the narrow Strait of Gibraltar.

Wherever you live near the sea, the pattern is the same: bigger ranges around full and new moon, smaller ones around the quarters.

Does the moon pull on the water in your body?

It is a popular idea. The body is mostly water, the moon moves oceans, so surely it tugs on us too. It sounds logical, and it does not hold up.

Tides do not depend on how much water something contains. They depend on how big the object is, because the tidal effect is the difference in the moon’s pull between the near side and the far side. Across a planet 12,700 km wide, that difference is enough to lift an ocean. Across a person less than two meters tall, it is millions of times smaller, far too small for any instrument to pick out, let alone your body.

You do not even need to look at people to see this. NOAA notes that the Great Lakes, hundreds of kilometers across, have true tides, but that their largest spring tides are less than five centimeters, easily swamped by wind and air pressure. A glass of water, a bathtub or a human body is smaller still. If you feel different around full moon, the explanations worth looking at are light, sleep and expectation, which is where the research on full moon and sleep and the studies on full moon births and emergency rooms come in.

None of this makes the moon less remarkable. The same tidal tug that moves the oceans once slowed the moon’s own spin until it kept one face toward us, which is why we always see the same side of the moon, and today it still pushes the moon away from Earth by about 3.8 cm a year.

The big tide dates of late 2026 and 2027

Every full and new moon brings a spring tide, but a few stand out because the moon is especially close.

1. December 24, 2026. The last full moon of 2026 is a supermoon at 356,729 km, even closer than any full moon of 2027. It falls at 01:28 UTC, so in the Americas it is still the evening of December 23. Local times are on the 2026 full moon page.
2. January 22, 2027. The Wolf Moon supermoon at 12:17 UTC and 357,635 km, the closest full moon of 2027 and the same date in every major time zone. Expect strong spring tides over the following day or two. The January full moon page lists local times.
3. February 20, 2027. The Snow Moon at 363,296 km is still close enough to give generous spring tides.
4. December 13, 2027. The Cold Moon at 368,131 km closes the year with the moon drawing near again.

At the other end, the Buck Moon of July 18, 2027 is the farthest full moon of the year at 405,968 km, so its spring tides are among the mildest of 2027.

Tide tables for your own coast will always be the final word, since local geography shifts the timing and the height. But the rhythm behind them is written in the moon’s calendar. All twelve full moons with exact UTC times are in the 2027 full moon calendar, the new moons that bring the other half of the spring tides are in the new moon calendar, and every distance is listed in the 2027 moon data.