King Tides

You’ve likely read about sea level rise and its impact on coastal communities. As most of the world lives within 50 miles of a sea or ocean, its impact will be widespread.  Despite all the warnings, many are waiting until the rise actually arrives.  It’s now arrived.  Here’s an article about what are called “King Tides” which are now flooding coastal communities – even if no storm is coming.  As it comes from a newspaper, some examples are based on the day the article was posted.  Suggestions follow.

•     •     •     •     • 

King tides, boosted

by sea-level rise, are

flooding communities

along the East Coast


What once happened only with a storm

is now routine on fair-weather days.


Matthew Cappucci

The Washington Post

Oct. 20, 2020


Despite tranquil weather to start this week, flooding has affected coastal communities from the Florida Keys to Maine. Long stretches of shoreline along the East Coast were inundated, water levels running a foot or more above normal. The swollen sea temporarily claimed streets, parking lots and public parks, and even seeped into homes, reminiscent of a storm surge.

But there was no storm to be found. In fact, many places enjoyed pleasant weather and sunshine. Yet coastal flood advisories plastered the coast, forcing road closures and flooding properties.


The culprit?

King tides.

A name informally attached to extra-high tides spurred by astronom-ical alignments, king tides often reach their peak in the fall. Decades ago, their impact was minimal. But added to the background of climate-driven sea-level rise, nowadays they are routinely problematic.

William Sweet, an oceanographer with NOAA specializing in sea level rise and flooding issues, said …


“I think of this like a stacking of phenomena. We

didn’t flood 30 or 40 years ago, but since then …

sea levels have been a half-foot to a foot higher.”


The rise in water has left thousands of homes and businesses vulnerable to sunny-day flooding, disrupting daily life and undermining property values in some areas.

As greenhouse gases resulting from human activity continue to accumulate in the atmosphere and warm the climate, sea-level rise and coastal inundation will only continue to grow with time, even on sunny days.


What are king tides, and why

are they greatest in the fall?


October is typically the worst month for king tide flooding, with some of the highest water levels of the year.

King tides are the highest tides that occur, and are easily predictable based on the orbits of the sun and the moon. Both celestial bodies exert a gravitational pull on the oceans, helping generate tides. The closer either body, the greater the tide.

Earth is closest to the sun in January, by a margin of more than 3.1 million miles compared to during June. That increases tides in the months leading up to and around the New Year.

High tides are then maximized when the moon reaches its closest point to Earth in its orbit, known as perigee, which occurred Friday.

Local weather plays a role in tides too and tends to enhance them in the fall. Along the East Coast, one of the biggest influences on tides is the Bermuda High, a high-pressure system anchored west of the Azores over the open Atlantic. Winds swirl in a clockwise pattern around it.

During the summer, flow around the Bermuda High brings heat and humidity to the Gulf and East Coasts and soupy conditions to the eastern United States. But during the winter, the Bermuda High shifts farther south and east, its influence on local winds dwindling. The onshore flow it generates is maximized in the summer and reaches a minimum during winter.

That means that the overlap of onshore winds and sun/moon-enhanced tides is greatest during the fall, particularly in the months of September, October and November. The tides are usually the most severe in October, having the most propensity for widespread impact. Waters are also still warm from summertime, and “thermal expansion” makes sea levels just a tad higher.

On Sunday, Monday and Tuesday, king tide flooding ran rampant up and down the East Coast, despite otherwise tepid weather.

In Key West, Fla., the National Weather Service warned that “flooded roads will probably be a mixture of rain and salt water” after heavy downpours moved through the area. The office posted a photo to Twitter showing the overnight flooding.

Flooding was reported in the Coconut Grove neighborhood of Miami, a location known for its susceptibility to even a minor spike in water level. The community sits barely a foot above sea level. Home values in the affluent area have been affected by the frequent flooding.  Walkways in public parks sat half a foot or more below water.

Miami, Jacksonville, Charleston and Wilmington, N.C., were all included in coastal flood advisories Tuesday.

Some roads were cut off in Mount Pleasant, S.C., while intersections were flooded in Charleston. Just last month, Charleston suffered a similar episode of king tide flooding, which hit much of the downtown area and medical district.

The shoreline flanking Washington, D.C., was placed under a coastal flood advisory Monday as well, while in Queens, N.Y., water bubbled up out of street drains on submerged streets.

In Boston, minor splashover was forecast and did occur, but issues were minimal since high pressure overhead suppressed the surge. Localized flooding was also noted farther to the north in northern New England.

•     •     •     •     •

Well, for decades, we’ve seen notices about projected sea-level rise. But we don’t always believe such projections.  And when we don’t personally feel the effect of the projected phenomena, we’re less prone to take action … especially if the action involves potential major shifts in where we live or how we live.  Here are three steps to consider …


First step:  Increasing awareness. In every city and county a person or department is designated to coordinate with FEMA. FEMA has maps available that show places that currently flood regularly, and places most susceptible to flooding in the future. Look at the maps, so you know where you stand.

Second step:  Call your home’s insurance agent. That individual can determine what your flood insurance will be, and whether they’ll insure you at all. If you have insurance, the company can’t cancel you. But they can opt to not provide insurance if you’re buying a home in an area which they see as flood prone. Money talks, so that’s a more definitive sign.

Third step:  Relocate – while you can. While many persist in living on water, those homes will soon lose their value as flooding becomes more prevalent. Change is happening. And change pushes us from our place of comfort … and often seems to do so at especially inconvenient times. Stay calm and have the courage to make the decisions that make the most sense.


About 50 years ago … George Allen was hired as coach of the Washington Redskins … ostensibly to rebuild a football team that had a long tradition of losing seasons. One of his first pronouncements:

”The future is now!”

That same thinking seems appropriate if you’re anywhere near a tidal coast.

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