What are "King Tides" and how do they work?

 

Before diving into king tides, it's first important to understand how tides work. This site does a great job of explaining what causes tides, but simply put, tides occur as a result of the moon's gravitational pull on our oceans. The height of tides depend mostly on where the moon is in its 28-day orbit around the Earth and on every 14th day, the moon and the sun line up with the Earth, creating a spring tide. That's why you can expect to see a spring tide on the same day you observe a full moon or a new moon! Some spring tides are higher than others based on how close the moon is to the Earth at that time.

A king tide is a non-scientific term used to explain exceptionally high spring tides called perigean spring tides. They occur during a new or full moon when the moon is in alignment with the sun AND in its closest point in orbit to the Earth (perigee), resulting in the greatest gravitational pull. You can explore the National Oceanic and Atmospheric Administration (NOAA) infographic below to better understand how perigean spring tides work.

 

perigeanspringtide-2-NOAA.jpg 

In Florida, king tides are generally experienced in the fall, when other seasonal factors like currents and temperature bring sea levels to their highest for the year. The exact timing of the highest tide is influenced by local factors such as water temperatures, rainfall, storms, and variations in ocean currents.


Flooding

NOAA High Tide Flooding Infographic 

NOAA High Tide Flooding Infographic - Click to enlarge image.

In low-lying areas, perigean spring tides can result in minor flooding. This flooding, which can lead to road closures, overwhelmed storm drains, and compromised infrastructure, is commonly called "nuisance flooding." 

According to NOAA, on average, nuisance flooding has increased about 50 percent in the last 20 years.

Major coastal flooding can occur when perigean spring tides occur simultaneously with strong onshore winds and barometric pressure changes from a coastal storm. Coupled with sea level rise, both minor and major coastal flood risks are expected to increase.

 

What can you do to adapt to nuisance flooding?

 

Currently, most king tide impacts are experienced by coastal property owners and those living in very low-lying areas near other water bodies. To study the elevation of your home, or see how sea level rise may affect your home, you can check out any of the interactive mapping resources located on our Mapping Tools webpage.  With one such tool, National Oceanic and Atmospheric Administration’s Sea Level Rise Viewer, you can zoom into your neighborhood, click the “High Tide Flooding" tab, and see areas in red that are vulnerable to King Tide flooding.

 

To PREPARE for a king tide, please consider the following options:

 

  • Have a plan in-place to move your vehicles to higher ground BEFORE a king tide event
  • Keep sandbags on-hand
  • Consider obtaining an elevation certificate from a licensed surveyor
  • Review your flood insurance policy, or consider acquiring flood insurance
  • Make a flood safety plan, and review it with your family/friends/co-workers
  • Study the elevation of the areas around your property and identify alternative routes to avoid driving through floods in the case of a king tide event
  • Remove waste carts and recycling bins from the curb as soon as possible when you are expecting a king tide event

To PROTECT yourself and your loved ones during or after a king tide, please:

 

  • Do not walk through flood water if possible. This can be a health and/or safety issue
  • If you do need to walk through flooded waters, practice good hygiene and wash your hands, clothes, and pets as soon as possible
  • Do not drive through flood waters if possible. This can be dangerous to you, and can damage your vehicle
  • Be aware of the new tidal range, and practice safe boating when traveling under a bridge. Check the tides before leaving the dock.
  • During king tide events, closely monitor your waste carts and recycling bins, and remove them from the curb as soon as possible as soon as they are emptied. If your property experiences flooding, consider storing your containers in a secure location until the next scheduled pick-up day.

 

 

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2019 King Tide Predictions

 

In 2019, coastal Palm Beach County can expect to experience the highest tides of the year during the last week of October. However, we should also be prepared for similar tides between 3.7 and 4.0 feet above MLLW* in late August, late September, and late November.

For reference, the average high tide for our area, based data gathered from the Lake Worth Pier tide gauge, is 2.88 feet above MLLW.

 

  • To see exactly what NOAA has predicted based on the Lake Worth Pier tide gauge, you can download this PDF document(2019 NOAA Tide Predictions.pdf)
    • Note: these predictions are based on gravitational forces only and offshore weather (winds, currents, and/or storms) often will magnify or diminish predicted tides.
  • Tide predictions and real time tidal data can be found at: NOAA Tides and Currents

 

NOAA water level and meteorological stations in Southeast Florida include: Lake Worth Pier, South Port Everglades, Virginia Key, Vaca Key and Key West.


*MLLW is the mean lower low water level, or the lowest low tide averaged over a 19-year period.