What is a King Tide?

Never head this term until a couple of years ago. Turns out there is not agreement as to the term “King Tide”

Wikipedia says:

A king tide is an especially high spring tide, especially the perigean spring tides which occur three or four times a year.

However NOAA says it’s another name for “Spring Tides”.

A spring tide —popularly known as a “King Tide”—refers to the ‘springing forth’ of the tide during new and full moon.

A neap tide —seven days after a spring tide—refers to a period of moderate tides when the sun and moon are at right angles to each other.

Bowditch doesn’t use the term:

Thus, when the Moon is at the point in its orbit nearest the Earth (at perigee), the lunar semidiurnal range is increased and perigean tides occur. When the Moon is farthest from the Earth (at apogee), the smaller apogean tides occur. When the Moon and Sun are in line and pulling together, as at new and full Moon, spring tides occur (the term spring has nothing to do with the season of year); when the Moon and Sun oppose each other, as at the quadratures, the smaller neap tides occur. When certain of these phenomena coincide, perigean spring tides and apogean neap tides occur.

It does point out that spring tides are not related to the seasons of the year.

Old English spring (noun), springan (verb), of Germanic origin; related to Dutch and German springen . Early use in the senses ‘head of a well’ and ‘rush out in a stream’ gave rise to the figurative use ‘originate’.

Springen is used in Dutch mainly with the verb to jump, it also means “to raise oneself in the air”. You could say that the tide raises itself in the air at that moment of extra high tide.

It is also described as: Rise from the sea to its highest mark.



  • What is a king tide?

In the simplest terms, king tide is colloquially used to describe an extremely high tide. Ordinary tides are caused by the gravitational pull between the Earth and the moon; king tides happen when astronomical events amplify that pull.*

For a while I thought it was just a PNW thing.

For years King Tides have been known in S. Florida, especially the paved over parts. Now with the increasing sea level it makes the news. Though this is dated one gets the idea that soon that part of the world will be uninhabitable. The water comes up thru the dead coral that Miami is built on. No dike will ever stop it.

Good grief. I guess I have to sell.

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The King Tide Conundrum: (PDF)

Evidently the “King Tide Project” in Australia originated the term, here is the conundrum:

Thus, our conundrum: Is a king tide defined by its cause (lunar and solar constituents, atmospheric disturbances) or its effect (observed water levels and flooding)?

Some definitions of a king tide is it’s the perigean spring tides while others definitions use actual water levels:

some places recognize a king tide based solely upon the water level. In South Carolina, a king tide is a spring tide greater than 2 m (6.6 ft) above mean lower low water (MLLW)

Using actual water levels seems more useful to the general public.

Toward Solving the Conundrum

The King Tides Project is a forward-thinking public engagement initiative that allows scientists and citizens to visualize the impacts of rising sea levels on their communities. As coastal scientists, we should actively participate in this conversation and contribute to the King Tide Initiative and other similar public outreach efforts. However, for the success of this and other king tide initiatives, a “king tide” must be defined consistently and accurately. The definition should include its cause and potential impacts. The definition should refrain from predicting an absolute number of occurrences but may state a minimum number of occurrences based on known celestial circumstances. We suggest: King tides occur during spring tides and atmospheric disturbances, such as the passing of a low pressure system or during an El Niño event. The impact of a king tide includes road closures, overwhelmed stormwater systems, damage to transportation infrastructure, and coastal erosion .

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