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Annual High Tide Flooding Outlook

A map showing the number of high tide flooding days at National Water Level Observation Network stations observed or projected for the selected year. Flooding thresholds are supplied by NOAA’s Office for Coastal Management.

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National

Frequencies of high tide flooding continue to increase across the Nation due to the long-term effects of relative sea level rise. Over the 2023-24 meteorological year (May to April) a strong El Niño cycle drove significant increases, particularly along the Atlantic Coast, contributing to a National average of 7 to 8 high tide flooding days. This year, as we move into La Niña conditions, most regions throughout the country will experience fewer flood days compared to last year. The Nation is predicted to experience 4 to 8 high tide flooding days for 2024-2025. NOAA is predicting an above-normal 2024 Atlantic hurricane season that has the potential to increase flooding for coastal communities along along the Atlantic and Gulf of Mexico. Today, the Nation experiences a median of 5 more flood days per year since 2000, a nearly 200% increase.

  • 34 stations met or exceeded station records from 2023-24, a steep increase from 8 stations breaking records throughout the 2022-23 meteorological year.
  • The Mid-Atlantic region experienced the greatest median number of flood days, 17, due to a combination of high sea level rise rates and strong El Niño influences. The Northeast and Pacific Islands tied for second with regional medians of 13 flood days.
  • Nearly half of NOAA’s long-term water level stations experienced flooding within the predicted range. Many stations experienced more flooding than expected due to an stronger El Niño influence than predicted.
  • This year, the Pacific Islands and the Western Gulf Coast are predicted to experience the greatest amount of high tide flooding; 5 to 16, and 7 to 15, respectively. These values are still very close to observations for the previous year, and are indicative of more routine flooding based on long-term sea level rise.

Note: Pacific Island flood thresholds were adjusted on June 1, 2023 to better match on-the-ground reports of flooding. This change impacts the Annual Outlooks for the Pacific Islands compared to previous years. Adjusted flood thresholds may not be representative of flooding around Kwajalein Island. Reported flood days represent the number of observed and predicted days where water levels exceed the flood threshold. The number of true flood days may be lower.

Northeast

The Northeast continues to experience rapid increases in high tide flooding due to the long-term effects of sea level rise. This region experienced an average of 13 flood days over the 2023-24 meteorological year. Increased high tide flooding during this time is due to El Niño conditions that elevated flood frequency along the Atlantic coast. This year, the Northeast is predicted to experience 7 to 12 high tide flood days. Increases in high tide flooding for the region are due mostly to ongoing sea level rise. NOAA is predicting an above-normal 2024 Atlantic hurricane season that has the potential to increase flooding for coastal communities over the coming year.

The Northeast is routinely impacted by high tide flooding primarily due to large tidal ranges and coastal storms, which often occur during the winter and spring seasons. Offshore storms typically bring winds from the east and northeast, piling up water over a wide, shallow continental shelf. Though the frequency of high tide flooding varies from year to year, the Northeast experiences a median of 6 more high tide flood days per year compared to the year 2000, an almost 150% increase.

Mid-Atlantic

The Mid-Atlantic continues to experience rapid increases in high tide flooding due to long-term effects of sea level rise. Recent rises in relative sea levels are caused by land subsidence, global sea level rise, and regional oceanographic effects. The Mid-Atlantic experienced a median of 17 flood days over the 2023-24 meteorological year, an increase of 10 days since the previous Outlook. Increased high tide flooding during this time is due to El Niño conditions that elevated flood frequency along the Atlantic coast that contribute through changes in wind patterns and storm activity. This year, the Mid-Atlantic is predicted to experience 7 to 12 high tide flood days. NOAA predicts an above-normal 2024 Atlantic hurricane season that has the potential to increase flooding for coastal communities over the coming year.

The Mid-Atlantic is routinely impacted by high tide flooding throughout the year due to its low lying coastal lands, wide/shallow continental shelf, and exposure to coastal storms. Coastal flooding in this region is predominantly weather driven, including both tropical systems coming up the coast from the south, and non-tropical offshore storms bringing winds and ocean currents from the east and northeast. Though the frequency of high tide flooding varies year to year, the Mid-Atlantic experiences an average of 7 more high tide flood days per year compared to the year 2000, a more than 200% increase.

Southeast

The southeast coast continues to experience increases in high tide flooding due to the long-term effects of sea level rise. Recent, rapid rises in relative sea level are caused by land subsidence, global sea level rise, and regional oceanographic effects. The region experienced a median of 10 flood days over the 2023-24 meteorological year. This year, the Southeast is predicted to experience 4 to 7 high tide flood days. NOAA predicts an above-normal 2024 Atlantic hurricane season that has the potential to increase flooding for coastal communities over the coming year.

  • Each state in the region set at least 1 record during the 2023-24 meteorological year: Charleston, SC experienced a record 17 flood days, while further down the coast, Fort Pulaski, GA saw a record 18 days. Fernandina Beach in northernmost Florida recorded 10 flood days, more than predicted.
  • Duck, NC observed the greatest amount of high tide flooding in the region, 22 days.
  • The 2024-25 Outlook predicts Trident Pier, FL will experience the greatest amount of high tide flooding with a range of 14 to 20 days.

This region of the U.S. is largely composed of low-lying areas prone to minor flooding. Coupled with land subsidence and global sea level rise, high tide flooding events have been observed more frequently over the past few decades. Due to relatively infrequent storm activity and a narrow continental shelf that limits the depth of storm surge, major flooding events are typically associated with Atlantic hurricanes and strong tropical storm systems. Northern parts of this region are sensitive to El Niño conditions that contributed to an increase in coastal storm activity during the 2023-24 Outlook season. Though the frequency of high tide flooding varies year to year, the Southeast now experiences an average of 5 more high tide flood days per year compared to the year 2000, a more than 500% increase.

East Gulf Coast

The Eastern Gulf Coast continues to experience increases in high tide flooding due to the long-term effects of sea level rise. Recent, rapid rises in relative sea levels are driven by land subsidence, global sea level rise, and regional oceanographic effects. This region experienced an average of 6 flood days throughout the 2023-24 meteorological year, largely due to sea level rise. This year, the Eastern Gulf Coast is predicted to experience between 3 to 7 high tide flood days. NOAA predicts an above-normal 2024 Atlantic hurricane season that has the potential to increase flooding for coastal communities over the coming year.

  • 4 stations in the region set records during the 2023-24 meteorological year. In Tampa Bay, where coastal communities are seeing an overall increase in high tide flooding, St. Petersburg, FL experienced a record 6 flood days, and neighboring Clearwater Beach, FL recorded 7 high tide flood days.
  • Bay Waveland, MS observed the greatest amount of high tide flooding in the region, 11 days, and is predicted to experience the highest range of flooding in the 2024-25 Outlook, 10 to 17 days..

This region of the country is routinely impacted by severe weather that often contributes to flood events, with extreme flooding usually caused by Atlantic hurricanes. Coupled with land subsidence and sea level rise, high tide flooding is even more frequent and impactful. Predictions for the region vary year to year due to large-scale weather and ocean current patterns. Overall, the eastern Gulf experiences a median of 3 more high tide flood days per year compared to the year 2000, a more than 200% increase.

West Gulf Coast

The Western Gulf Coast continues to experience rapid increases in high tide flooding due to the long-term effects of sea level rise. Recent rises in relative sea levels are caused by land subsidence, global sea level rise, and regional oceanographic effects. This region experienced an median of 5 flood days throughout the 2023-24 meteorological year, fewer than previous years. This year, the western Gulf Coast is predicted to experience between 7 to 15 high tide flood days, the highest for the continental U.S. NOAA is predicting an above-normal 2024 Atlantic hurricane season that has the potential to increase flooding for coastal communities over the coming year.

  • Eagle Point, TX experienced the greatest amount of flooding during the 2023-24 meteorological year, 28 days; and is also predicted to experience the most in the 2024-25 Outlook with a range of 21 to 43 days.
  • Galveston Pier, TX, situated along the channel closer to the Gulf, experienced the second greatest amount of flooding, 23 days, more than predicted.

The western Gulf is a region frequently impacted by high tide flooding due to high rates of land subsidence, with extreme coastal flooding occurring during Atlantic hurricanes. Though high tide flooding varies greatly from year to year, the western Gulf now experiences an average of 8 more high tide flood days per year compared to the year 2000, a more than 300% increase.

Note: Reported flood days represent the number of observed and predicted days where water levels exceed a flood threshold. The number of true flood days may be lower.

Southwest

The Southwest Coast continues to experience increases in high tide flooding due to long-term effects of sea level rise. Recent rises in relative sea levels are caused by global sea level rise and regional oceanographic effects. The region experienced an median of 1 to 2 flood days throughout the 2023-24 meteorological year. Increases in high tide flooding in the Southwest are attributed to tidal flooding caused by El Niño conditions. This year, the region is predicted to experience up to 3 high tide flood days, down from previous years due to La Niña conditions.

  • Similar to previous years, North Spit, Humboldt Bay, CA experienced record setting flooding over the 2023-24 meteorological year with 19 flood days, more than predicted, likely due to El Niño conditions. This was the highest number of flood days recorded in the region.
  • Stations in the southern areas of this region also experienced more flooding than predicted due to El Niño: La Jolla, CA observed 6 days and San Diego, CA recorded 12 days
  • This year, the 2024-25 Outlook predicts, North Spit, Humboldt Bay, CA will again experience the greatest amount of high tide flooding, 7 to 13 days.

High tide flooding outlooks vary by region to account for differences in the coastline that contribute to flood events. In general, the narrow continental shelf and relatively infrequent coastal storms systems limit the frequency of significant flood events although this region can experience damaging flood levels from high waves. Increased flood frequencies in this region are highly dependent upon El Niño conditions, which brings warmer water to the coast and contributes to higher sea levels, increasing the likelihood for minor, frequent flooding. Higher sea levels allow for very high tides, like king tides, to inundate a larger extent, creating greater impacts. Though high tide flooding varies greatly each year, overall, the Southwest experiences an average of 1 more high tide flood days per year compared to the year 2000, a nearly 150% increase.

Northwest

The Northwest continues to experience increases in high tide flooding due to long-term effects of sea level rise. Recent rises in relative sea levels are caused by land subsidence, global sea level rise, and regional oceanographic effects. The region experienced an median of 2 high tide flood days throughout the 2023-24 meteorological year, predominantly due to El Niño conditions that bring additional oceanographic and atmospheric effects. The fewer number of days can be partially attributed to vertical land motion. This year, the region is predicted to experience up to 7 high tide flooding days.

  • Similar to previous years, Toke Point, WA experienced the greatest amount of flooding over the 2023-24 meteorological year with 13 days, within the predicted range.
  • This year, the 2024-25 Outlook predicts, Toke Point, WA will again experience the greatest amount of high tide flooding, 3 to 16 days.

Flooding in the Pacific Northwest is less tidally driven and more often the result of extreme weather events and ocean currents. The wide, shallow continental shelf of the Pacific coast can amplify storm surge, often flooding low-lying areas. Year to year variations in high tide flood frequency in this region is highly associated with El Niño conditions. High tide flooding in the northwest remains relatively consistent to observed values in the year 2000.

Note: Reported flood days represent the number of observed and predicted days where water levels exceed a flood threshold. The number of true flood days may be lower.

Pacific Islands

The Pacific Islands continue to experience rapid increases in high tide flooding due to the long-term effects of sea level rise. Recent rises in relative sea levels can be attributed to land subsidence, global sea level rise, and regional oceanographic effects. El Niño conditions contributed to coastal flooding during the 2023-24 meteorological year. This year, fewer are predicted with the return of La Niña conditions. The region experienced an average of 13 flood days during the 2023-24 meteorological year. This year, the western Pacific Islands are predicted to experience 5 to 16 high tide flood days, the greatest predicted range out of all regions.

  • Nawiliwili, HI on the Island of Kauai experienced a record number of flood days during the 2023-24 meteorological year, 29 days.
  • More than half of stations in the Pacific region recorded flooding within the predicted range. The Pacific Islands are predicted to experience the greatest amount of flooding over the coming year.
  • Kwajalein Island, Marshall Islands observed the greatest amount of flooding in the region, 47 days, and is predicted to again experience the highest number of flood days for the 2024-25 Outlook, 78 to 97 days.
  • Though the frequency of high tide flooding varies from year to year, the Pacific Islands experience a median of 7 more high tide flood days per year compared to the year 2000, a more than 250% increase . This can also be attributed to anomalously warm water that contributes to elevated sea levels and high tide flooding in the region.

Note: Pacific Island flood thresholds were adjusted on June 1, 2023 to better match on-the-ground reports of flooding. This change impacts the Annual Outlooks for the Pacific Islands compared to previous years. Adjusted flood thresholds may not be representative of flooding around Kwajalein Island. Reported flood days represent the number of observed and predicted days where water levels exceed the flood threshold at the Kwajalein station. The number of true flood days may be lower.

Pacific Islands

The Pacific Islands continue to experience rapid increases in high tide flooding due to the long-term effects of sea level rise. Recent rises in relative sea levels can be attributed to land subsidence, global sea level rise, and regional oceanographic effects. El Niño conditions contributed to coastal flooding during the 2023-24 meteorological year. This year, fewer are predicted with the return of La Niña conditions. The region experienced an average of 13 flood days during the 2023-24 meteorological year. This year, the eastern Pacific Islands are predicted to experience 5 to 16 high tide flood days, the greatest predicted range out of all regions.

  • Nawiliwili, HI on the Island of Kauai experienced a record number of flood days during the 2023-24 meteorological year, 29 days.
  • More than half of stations in the Pacific region recorded flooding within the predicted range. The Pacific Islands are predicted to experience the greatest amount of flooding over the coming year.
  • Kwajalein Island, Marshall Islands observed the greatest amount of flooding in the region, 47 days, and is predicted to again experience the highest number of flood days for the 2024-25 Outlook, 78 to 97 days.
  • Though the frequency of high tide flooding varies from year to year, the Pacific Islands experience a median of 7 more high tide flood days per year compared to the year 2000, a more than 250% increase . This can also be attributed to anomalously warm water that contributes to elevated sea levels and high tide flooding in the region.

Note: Pacific Island flood thresholds were adjusted on June 1, 2023 to better match on-the-ground reports of flooding. This change impacts the Annual Outlooks for the Pacific Islands compared to previous years. Adjusted flood thresholds may not be representative of flooding around Kwajalein Island. Reported flood days represent the number of observed and predicted days where water levels exceed the flood threshold at the Kwajalein station. The number of true flood days may be lower.

Alaska

NOAA collects valuable oceanographic and meteorological information from water level stations across Alaska. Based on these long-term records, several factors make predicting high tide flooding in the region challenging.

  • NOAA is still working to establish consistent and representative high tide flooding thresholds throughout Alaska.
  • Many locations experience extreme tide ranges making it less likely a storm surge event will overlap with a high tide and create impacts.
  • Coastal topography is steeper than other areas of the U.S., limiting areas that would be exposed to high tide flooding.
  • Very few locations have tidal-to-geodetic elevation connections needed to empirically associate and map the extent and severity of inland flooding.
  • Infrastructure is often placed in more protected areas away from the coast to limit exposure to extreme conditions in remote areas.
  • Relative sea level is decreasing across much of Alaska due to glacial uplift, making coastal flooding less likely in the future.

Additional details and information can be found in Patterns and Projections of High Tide Flooding Along the U.S. Coastline Using a Common Impact Threshold. Near- and real-time flood conditions can be monitored through the Coastal Inundation Dashboard.

Caribbean Islands

The Caribbean does not show a long-term trend in high tide flooding days. Overall, the region did not experience high tide flooding over the 2023-24 meteorological year. This year, the Caribbean is predicted to experience very few flood days, less than 1 day on average. Flooding in this region is less tidally driven. NOAA predicts an above-normal Atlantic hurricane season that has the potential to increase flood frequencies in the region over the coming year.

  • Similar to previous years, Magueyes Island, PR observed the greatest amount of flooding over the 2023-24 meteorological year, 1 day.
  • The 2024-25 Outlook again predicts Magueyes Island, PR will experience the greatest number of high tide related flood days in the region, up to 1 day.

Flooding in the Caribbean Islands is less tidally driven and more often the result of waves and weather events. For this reason, minor flooding thresholds for the region are typically higher than average high tides. However, this does not preclude flooding that might occur at slightly lower heights, or flooding driven by extreme weather events, like hurricanes.

Flooding at high tide in Newport, Rhode Island

Flooding at high tide in Newport, Rhode Island.

Photo Credit: MyCoast.Org, Rhode Island, 10/20/24.

Location: Brenton Cove, King Park, Newport, Rhode Island

Flodding Millsboro, Deleware

Cars driving along Long Neck Road between Rehoboth Bay & Indian River Bay encountered flooding due to simultaneous above normal high tide and new moon, which was exacerbated by multiple rounds of rain and onshore winds.

Photo Credit: Driscoll Drones, 2/25/2020.

Location: Long Neck Road, Millsboro, DE

Cars travel through high water Charleston, South Carolina

Cars travel through high water on E. Bay St in front of Sanders-Clyde Elementary School in Charleston, SC. The high tide flooding was due to a perigean spring tide.

Photo Credit: Sean Bath, 9/11/2014.

Location: Charleston, SC

Flooding on street in Dauphin Island Alabama

High tide flooding on a sunny day in St. Petersburg, Florida.

Photo Credit: Heidi Stiller, NOAA’s Office of Coast Management

Location: Coffee Pot Park, St. Petersburg, Florida. September, 2023

Flooding on street in Galveston Island Texas

Persistently elevated water levels in West Bay cause high tide street flooding on Galveston Island around Jamaica Beach.

Photo Credit: Sheri Cortez, 6/25/2020.

Location: Jamaica Beach, TX

Minor flooding Camano Island Washington

Minor high tide flooding blocks roadway on Camano Island.

Photo Credit: MyCoast, 12/30/2022

Location: Camano Island, Washington

Aerial photo of king tide at Manzanita Junction, Mill Valley, California

Aerial photo of the king tide at Manzanita Junction, Mill Valley. Water levels were higher than normal due to a perigean spring tide.

Photo Credit: California Coast Commission, 12/4/2021.

Location: Manzanita Junction, Mill Valley, CA

An aerial view of the flooding during an above normal high tide in Kwigillingok, Alaska

An aerial view of the flooding during an above normal high tide in Kwigillingok.

Photo Credit: Jesse Igkurak, 6/24/2021.

Location: Kwigillingok, Bering Sea Coast, AK

Water spilling over from Makaiwa Bay into Kalahuipua'a Fishponds during an above normal high tide on July 3, 2016

Water spilling over from Makaiwa Bay into Kalahuipua'a Fishponds during an above normal high tide on July 3, 2016.

Photo Credit: Chris Peters

Location: Kalahuipua'a fishponds, at Mauna Lani Hotel, Waimea, Hawaii

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About the Annual Outlook

Above-normal tides can trigger high tide flooding, disrupting coastal communities. This flooding can occur on sunny days and in the absence of storms. More severe flooding may occur if high tides coincide with heavy rains, strong winds, or large waves. As sea levels continue to rise, our coastal communities will experience more frequent high tide flooding - a National average of 45 to 85 days per year by 2050. Predicting the frequency of high tide flooding in the future helps coastal communities plan for and mitigate flooding impacts.

The Annual High Tide Flooding Outlook provides the number of high tide flooding days predicted for the coming meteorological year (May to April). Data is supplemented with decadal projections for the year 2050, sea level rise scenarios, and high tide flood exposure maps to support long-term coastal planning. Summaries are provided for each region to account for geographical differences at the coast, and are accompanied by regional graphics to demonstrate potential high tide flooding impacts.

Using This Product

Begin by selecting a region and year from the drop down menu, or clicking a station on the map to see the number of observed and projected high tide flooding days. Click the region tab to learn more about regional drivers of higher water levels and potential high tide flooding impacts.

  1. Map View: Visualize high tide flooding observations and projections at NOS water level stations. Navigate the map by selecting a region from the drop-down menu or using the pan/zoom tools. Stations are color-coded to show flood frequencies for select meteorological years, the annual outlook year, and the projection for 2050.
  2. Region View: Learn why the annual outlook may be higher or lower than previous years for a selected region, and what coastal flooding impacts the region may experience as a result of its unique geographic characteristics.
  3. Station View: Interact with the current range of high tide flooding projection values and historical flood observations since 2000 to understand changes in flood frequency through time.
  4. Projection View: Interact with station-based decadal projections and sea level rise scenarios to understand and plan for future flooding impacts.

Underlying Science

The frequency of high tide flooding varies from year to year due to large-scale changes in weather and ocean circulation patterns, such as the phase of the El Niño Southern Oscillation (ENSO). The Annual Outlook uses a statistical model that derives a range of high tide flooding days predicted for each National Ocean Service (NOS) water level station over the coming meteorological year, May to April. The model combines historical flood observations (relative to established NOS flood thresholds) with the Oceanic Niño Index (ONI) and the 3- month average of sea-surface temperature anomalies. Decadal projections are based on a statistical fit of historical water level observations and the sea level rise scenarios outlined in the Sea Level Rise Technical Report. Each decade consists of an average of annual values calculated from data points from the previous ten years. Additional details about the methodology are detailed in Sweet, et al. 2018.

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