King Tides & High Tides

Monroe County will experience seasonal high king tides from September through December. King tides are unusually high tides that occur several times a year, usually in the fall, that can cause coastal tidal flooding, especially in low-lying areas. Monroe County is monitoring unincorporated areas experiencing these high tides. Residents and visitors are encouraged to prepare for king tides, be aware of their surroundings, and avoid driving on flooded streets.

2021 Expected Dates

In coordination with the National Weather Service in Key West, the highest king tides are expected to occur Oct. 8-11, Nov. 5-9, and Dec. 4-6. However, king tide flooding can generally be anticipated anytime during the following dates: Sept. 11-13, Sept. 17-20, Oct. 4-13, Oct. 21-23, Nov. 3-11, and Dec. 2-8.  

Check the latest weather forecast at Heavy rainfall can add to king tide flooding, resulting in deeper water and additional hazards in streets and neighborhoods.

Submit Photos

If done safely, residents can provide photos of property or neighborhoods experiencing tidal flooding to with the address, date, and time the photos were taken. Photos can assist in future planning and will become the property of Monroe County. By submitting a photo, you agree to allow the County to use it in any manner the County desires.

How To Stay Safe

  • Avoid walking through floodwaters, it is dangerous and can be a health hazard.
  • Adjust your driving schedule accordingly and do not drive through flooded areas. Turn around and find another way if possible. It is likely saltwater. It is unsafe and can cause short and long-term damage to your vehicle. If you drive through tidal floods, wash the undercarriage of your car to remove any saltwater accumulation.
  • Follow posted road closure and detour signs.
  • If you drive through flooded areas, please note that creating waves can cause additional damage to the surrounding landscaping and property.
  • Avoid parking your vehicle in low-lying areas that are prone to flooding to prevent saltwater damage to your vehicle.
  • Be careful of hazards below the surface that you cannot see that can cause injury from things like nails, broken glass, debris, and displaced utility hole covers.
  • If you are a boater, be aware that these high tides cause lower clearances under fixed bridges. Check the tides before leaving the dock.

Review additional information on flood insurance rate maps, coastal high hazard areas, property flood depths, natural conservation areas and wetlands, flood insurance, and floodplain management regulations.

What is a Tide?

The word “tide” is a generic term used to define the rise and fall of sea level with respect to land. Tides are influenced by the gravitational attraction of the moon and sun. In addition, tides are affected by other factors such as coastline configuration, local water depth, wind, and weather conditions. Twice a day, tides peak to a high and low water level, commonly referred to as “high tide” and “low tide.”

Knowledge of the tide times and predicted heights are important to various applications such as emergency preparedness; maritime navigation; the construction of bridges, docks, and seawalls; and the operation of wastewater and stormwater collection systems. Tide information is used for fishing, boating, and other water-related industries. Currently, this information is critical to understanding flooding which impacts the County during weather events, particularly in low-lying areas.

To find tides in your area, visit (Put in a zip code, or city and state, and it will use the closest station data with today's tides as well as measured water levels.)

Tide Predictions

Tide predictions can differ from the actual sea level rise or fall that occurs. Predicted tidal heights are those expected during average weather conditions. When weather conditions differ from what is considered average, water levels can be significantly altered. Generally, prolonged onshore winds (wind towards the land) or low barometric pressure can produce higher sea levels than predicted, while offshore winds (wind away from the land) and high barometric pressure can result in lower sea levels than predicted.

High tides are produced from the flow of water toward positions on Earth where the gravitational forces of the sun and moon are the strongest. Low tides are created at a point midway between the two positions. The alternating between high and low tides are caused by the daily rotation of the Earth. There are peak high tides each month. Typically the Florida Keys experiences its highest tides during the months of September, October, and November.

These high tides may cause ocean and canal waters to rise above elevations of land, including streets and seawalls in low-lying areas throughout South Florida, causing tidal flooding in those areas. Onshore winds can increase coastal flooding and rain events may increase incidences of flooding further inland as the high tides impede drainage.

To reduce flooding from tides, the County is currently using Tiger Dams in some areas to lessen the effects of tidal waters.

Insure Your Property

Homeowner and renter insurance policies usually do not cover flood damage. Monroe County encourages neighbors who rent or own property in the Florida Keys to purchase flood insurance to protect their homes and possessions against loss from flood damage.  

Protect Your Property

Neighbors that drive through tidally flooded streets should consider taking their vehicles through a car wash equipped with an undercarriage sprayer to remove the saltwater.

Storm Drains

State law prohibits dumping anything into the storm drain system and unauthorized obstructions or alterations of the drainage features. Residents should report illegal dumping into the stormwater system or clogged storm drains by calling 9-1-1 if they see it happening.

Residents can help prevent flooding and stormwater pollution by:

  • Keeping pollutants or chemicals out of the storm drains,
  • Keeping swales, yards and other surfaces clear of debris so that water can drain into the soil rather than running off and causing flooding,
  • Removing debris from nearby storm drains so water may flow freely into them,
  • Landscaping with native, drought-friendly plants that absorb water and require little or no fertilizer.

Useful Resources 

Neighbors may visit the following links for additional information: