Chris
Staff member
Welcome to the tides web app which has been serving the public since 2004.
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Tides are the regular rise and fall of sea levels caused primarily by the gravitational pull of the moon and, to a lesser extent, the sun on Earth's oceans. Here’s how it works in simple terms:
The moon’s gravity tugs on the water closest to it, pulling it toward the moon and creating a bulge—a high tide—in that area. On the opposite side of Earth, there’s another high tide, not because the moon is pulling it, but because the Earth itself is being pulled more strongly toward the moon than the water on the far side, leaving that water "behind" to form a second bulge. The areas between these bulges experience low tides.
As Earth rotates on its axis once every 24 hours, any given spot on the coast moves through these bulges and dips, typically giving us two high tides and two low tides each day—about every 12 hours and 25 minutes, since the moon is also orbiting Earth and shifting the pattern slightly.
The sun plays a role too, though its pull is weaker because it’s so much farther away. When the sun, moon, and Earth align (during full or new moons), the tides get extra high and low—called spring tides. When they’re at right angles (quarter moons), the tides are more moderate—called neap tides.
Other factors like coastline shape, ocean depth, and weather (winds or storms) can tweak how tides look locally, but the moon’s gravity is the main driver. That’s why tides are predictable and follow lunar cycles, not random whims. Coastal folks have been tracking this dance for millennia—it’s as reliable as the moon showing up each night.
When you register you can subscribe for member access. Members experience is without future date restrictions and without ads. Printing calendars for your reference or for your guests is available. The free service includes restrictions on the future content and is displayed with some ads.
Thank you for visiting. If you have a question about the site or your account and would like to speak with me, click on my name to start a conversation.
Tides are the regular rise and fall of sea levels caused primarily by the gravitational pull of the moon and, to a lesser extent, the sun on Earth's oceans. Here’s how it works in simple terms:
The moon’s gravity tugs on the water closest to it, pulling it toward the moon and creating a bulge—a high tide—in that area. On the opposite side of Earth, there’s another high tide, not because the moon is pulling it, but because the Earth itself is being pulled more strongly toward the moon than the water on the far side, leaving that water "behind" to form a second bulge. The areas between these bulges experience low tides.
As Earth rotates on its axis once every 24 hours, any given spot on the coast moves through these bulges and dips, typically giving us two high tides and two low tides each day—about every 12 hours and 25 minutes, since the moon is also orbiting Earth and shifting the pattern slightly.
The sun plays a role too, though its pull is weaker because it’s so much farther away. When the sun, moon, and Earth align (during full or new moons), the tides get extra high and low—called spring tides. When they’re at right angles (quarter moons), the tides are more moderate—called neap tides.
Other factors like coastline shape, ocean depth, and weather (winds or storms) can tweak how tides look locally, but the moon’s gravity is the main driver. That’s why tides are predictable and follow lunar cycles, not random whims. Coastal folks have been tracking this dance for millennia—it’s as reliable as the moon showing up each night.
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