CO-OPS Products - NOAA Tides & Currents (2023)

Tides & Currents Products

NOAA's Tides and Currents website, developed and supported by the Center for Operational Oceanographic Products and Services (CO-OPS), provides the following products. A definition of each term and a description of each product are provided.

Tides / Water Levels

The periodic rise and fall of a body of water resulting from gravitational interactions among the sun, moon, and earth. The vertical component of the particulate motion of a tidal wave. Users can retrieve data from active or historic stations.

Water Level Landing Page
Water Levels

The height of the level of water relative to a Datum. Most stations with water level sensors provide readings every six minutes. Some, such as the 1-minute water level stations, provide readings once a minute. CO-OPS measures water levels at coastal stations and at many stations located around the Great Lakes. For coastal stations, water levels have a periodic rise and fall resulting from gravitational interactions among the sun, moon, and earth. For Great Lakes stations, changes in water level are usually due to weather events.

1-minute Water Level Data

CO-OPS provides real-time access to 1-minute water level data to support tsunami detection, warning, and modeling, and support warning and mitigation of other coastal hazards. Data can be viewed numerically or graphically.

NOAA Tide Predictions

A calculation of what the water level will be based on harmonic constituents (see below). This site offers six-minute and hourly tide/water level predictions "on-the-fly" for all stations with harmonic constituents. It also offers high/low data for all stations in NOAA's published tide and current table.

The site is updated every quarter; during the first two weeks of January, April, July and October. The quarterly updates may include the addition of new stations, updating subordinate and harmonic stations, and removal of superseded stations.

(Video) The Value of Accurate Water Levels

Harmonic Constituents

One of the harmonic elements in a mathematical expression for the tide-producing force and in corresponding formulas for the tide or tidal current. Each constituent represents a periodic change or variation in the relative positions of the earth, moon, and sun. A single constituent is usually written in the form y = A cos (at + "), in which y is a function of time as expressed by the symbol t and is reckoned from a specific origin. The coefficient A is called the amplitude of the constituent and is a measure of its relative importance. The angle (at + ") changes uniformly and its value at any time is called the phase of the constituent. The speed of the constituent is the rate of change in its phase and is represented by the symbol "a" in the formula. The quantity is the phase of the constituent at the initial instant from which the time is reckoned. The period of the constituent is the time required for the phase to change through 360° and is the cycle of the astronomical condition represented by the constituent.


For marine applications, a base elevation used as a reference from which to reckon heights or depths. It is called a tidal datum when defined in terms of a certain phase of the tide. Tidal datums are local datums and should not be extended into areas that have differing hydrographic characteristics without substantiating measurements. In order that they may be recovered when needed, such datums are referenced to fixed points known as benchmarks. The "Present Epoch" is from 1983-2001 and includes the latest datums available. The "Superseded Epoch" is from 1960-1978 and has been replaced by the "Present" datums, or was not replaced due to insufficient data.

Bench Mark Data Sheets

A fixed physical object or mark used as reference for a horizontal or vertical datum. A tidal bench mark is one near a tide station to which the tide staff and tidal datums are referred. A primary bench mark is the principal mark of a group of tidal bench marks to which the tide staff and tidal datums are referred. The standard tidal bench mark of the National Ocean Service is a brass, bronze, or aluminum alloy disk 3 1/2 inches in diameter containing the inscription NATIONAL OCEAN SERVICE together with other individual identifying information. The "Present Epoch" is from 1983-2001 and is the latest bench mark sheet available. The "Superseded Epoch" is from 1960-1978 and has been replaced by a "Present" sheet or was not replaced due to insufficient data.

Sea Level Trends

The rate of mean sea level rise or fall has been determined for 117 long-term water level stations. Monthly mean sea level data were used to obtain the linear trend, the average seasonal cycle, and the interannual variations. The linear trend at a coastal location is primarily a combination of the global sea-level rise and any local vertical land movement. The seasonal cycle and interannual variations are caused by fluctuations in coastal ocean temperatures, salinities, winds, atmospheric pressures, and currents. The interannual variations for many Pacific stations are closely related to the El Nino/Southern Oscillation. Assuming no change in trend, the time series of interannual variations are extended up to the latest month, and maps are created to show the regional extent of anomalously high or low water levels.

Sea Level Trends are available for both coastal and global stations.

Extreme Water Levels

Exceedance Probability Statistics on Extreme Water Levels now available for select water level stations in California, Oregon, Washington, and the Pacific Islands.

(Video) Video Tutorial on Tide Predictions


Various water level reports in table and report format.

Coastal Inundation Dashboard

Provides real-time and historical coastal flood information at select locations.


CO-OPS Publications

The publications section is an extensive collection of CO-OPS recent and historic publications, including informational pamphlets, technical reports, technical memorandums, manuals and standards publications, storm reports, historical data reports and other popular publications. Most of the publications are available via PDF, others are described by an abstract and information on how to obtain them.

CO-OPS Field Library

The CO-OPS Field Library is a public document repository for manuals, standard operating procedures, publications and other documents and is maintained by the Center for Operational Oceanographic Products and Services (CO-OPS). Documents may be searched using title, author, and keyword/tags and can be downloaded using the filename link.

Historic Tide and Tidal Current Tables

NOAA's National Ocean Services (NOS) and predecessor offices have been annually publishing tide and tidal current predictions in hard-copy format, entitled "Tide Tables" and "Tidal Current Tables", since the 1860's. Electronic copies of the published "Tide Tables" and "Tidal Current Tables" from past year, as PDF documents, are made available through this page of the Tides & Currents website. Additional historic publications of the "Tide Tables" and "Tidal Current Tables" will be made available when they are converted to an electronic format.


Current's Landing Page

Generally, a horizontal movement of water. Currents may be classified as tidal and nontidal. Tidal currents are caused by gravitational interactions among the sun, moon, and earth and are part of the same general movement of the sea that is manifested in the vertical rise and fall, called tide. Tidal currents are periodic, with a net velocity of zero over the particular tidal cycle. See tidalwave. Nontidal currents include the permanent currents in the general circulatory systems of the sea, as well as temporary currents arising from more pronounced meteorological variability.

(Video) Ashley Welty sea level rise

Historic Current Data

Each year, CO-OPS measures currents at many coastal locations in order to provide accurate tidal current predictions for the maritime community. These data sets typically range from one to three months in length and at most locations, data are available throughout the water column. This page contains the raw current measurements taken during these surveys, which date back to 1997.

NOAA Current Predictions

This new site offers expanded tidal current predictions for stations in NOAA's published tide and current tables. Customized predictions are calculated "on-the-fly" and are available in graphical and text format. Six-minute, half-hour and hourly tidal current predictions can be generated for all stations with harmonic constituents. The product also offers predicted time and speed of maximum flood/ebb and timing of slack water (no current) for all stations in NOAA's published current tables. Predictions can be downloaded in text, CSV, XML and PDF formats.

HF Radar Surface Currents

This product provides near real-time surface current observations and tidal current predictions from High Frequency Radar in estuarine and coastal locations. Hourly surface currents are presented via an interactive map and time series plots for 48 hours before and 48 hours after the present time.


Meteorological and Other Oceanographic Data Landing Page
Meteorological Observations

Many stations are equipped with meteorological sensors to collect meteorological observations in conjunction with water level data. The following observations may be retrieved from this website: wind speed and directions, air temperature, water temperature, barometric pressure, relative humidity, and visibility. Not every station has the full suite of sensors installed.

Water Temp/Conductivity

Water temperature and/or conductivity observations.


Of all the constituents, the moon has the greatest effect on tides. This page provides information on the various phases of the moon.

(Video) Bringing Sea Level Rise to Life Using GIS and Python

Physical Oceanographic Real-Time System (PORTS®)

PORTS® Landing Page

PORTS® is a decision support tool that improves the safety and efficiency of maritime commerce and coastal resource management through the integration of real-time environmental observations and predictions.


MyPORTS is an application designed to let you create your own customized PORTS® pages.


Operational Forecast Systems

Nowcasts and forecast guidance are scientific predictions about the present and future states, respectively, of water levels (and possibly currents and other relevant oceanographic variables, such as salinity and temperature) in a coastal area made by a numerical model. These predictions rely on either observed or forecast data. A nowcast incorporates recent (and often near real-time) observed meteorological, oceanographic, and/or river flow rate data. A nowcast covers the period of time from the recent past (e.g., the past few days) to the present, and it makes predictions for locations where observational data are not available. The present is the time at which the nowcast is made, and at which the most recent observations are from a few minutes to an hour old. A forecast guidance incorporates meteorological, oceanographic, and/or river flow rate forecasts and makes predictions for locations where observational data will not be available. A forecast guidance is usually initialized by the results of a nowcast.

Links / Web Services

Web Services Landing Page
IOOS Data Portal

This is your gateway to the Center for Operational Oceanographic Products and Services (CO-OPS) one stop for data access using NOAA's Integrated Ocean Observing System (IOOS) Sensor Observational Service, Web Services, OPeNDAP, NetCDF model data, stations information and other services.


NowCOAST is a web mapping portal providing spatially referenced links to thousands of real-time coastal observations and NOAA forecasts of interest to the marine community.

Storm QuickLooks

The Storm QuickLook product provides a real-time synopsis of oceanographic information when coastal areas are threatened by a tropical storm or hurricane. The product integrates water level and meteorological observations with National Weather Service tropical cyclone track and intensity information.

(Video) Ocean Currents, Waves and Sea State - W Frank Bohlen

GIS Data Portal

The CO-OPS GIS Data Portal provides public access to CO-OPS stations and derived data products in the form of GIS services, including as public ArcGIS Server REST Services. The services include OGC compliant Web Feature Services (WFS), providing full access to attributes.

The station map is a convenient zoomable interface that allows the user to quickly identify an area of interest, such as a state, and see all active observing stations in that area with a listing of the types of data available at each site. Hovering the mouse over the site icon reveals the latest data listing, and clicking on the icon will bring up the data graphs below the map. Search criteria along the right margin allow the user to identify various data products, geographic regions, or data types from both active and historical sites.


The CO-OPS Data API is a flexible retrieval mechanism for direct access to CO-OPS' products, such as water levels, predictions, currents, meteorological observations, and more. Users can retrieve output in multiple common formats.


Where can I download tide data? ›

Tide and current data is available from NOAA's Center for Operational Oceanographic Products and Services website.

Why are tide charts different? ›

The most accurate tidal predictions usually exist for places located on the coast because they are less affected by winds and other meteorological events. Areas with shallow water or in a bay are more affected by alternate factors.

What are current tables? ›

Tide tables or charts list the daily high and low tides for all the tide stations in a given area for an entire year. Current tables list the maximum flood and ebb and the times of high and low slack current.

Where are the strongest tidal currents in us? ›

The swift currents of the Piscataqua River make Portsmouth Harbor one of the fastest flowing tidal waterways in the Continental United States (NOAA list of 50 fastest in North America).

What is tide gauge data? ›

Tide gauge data are used to validate ocean models and to detect errors and drifts in satellite altimetry. Compared to satellite data, tide gauge data offer a longer record and finer temporal resolution but coarser spatial resolution.

How do you find water current? ›

How we measure currents. The two main components of currents are speed and direction. To measure a current, toss an object into the water and time how long it takes to get to a certain point a known distance away. Granted, technology allows us to be a little more accurate and sophisticated in our measurements.

What are the four 4 types of tides? ›

Flood Tide – Over a period of several hours there will be a rise in sea level. High Tide – This is a stage where the water reaches its maximum level. Ebb Tide – This is a stage where sea level keeps receding over several hours. Low Tide – The Level of Seawater stops receding.

Which tide chart is most accurate? ›

Online predictions are more accurate and up-to-date than what is provided in the annual printed tables. NOAA tide predictions are used by both commercial and recreational mariners for safe navigation.

Where is there only one tide a day? ›

Some areas, such as the Gulf of Mexico, have only one high and one low tide each day. This is called a diurnal tide.

What tide is best for fishing? ›

An incoming tide, or rising tide, is considered one of the best fishing tide times. Water that enters an estuary area from the ocean can have a lower temperature, contain more oxygen, and have better clarity than the water that exists in the estuary during low tide or slack water periods.

How do I read my tidal current chart? ›

How To Read Tide Charts 101 (For Boating Safety & Catching More Fish)

How far in advance can tide times be predicted? ›

NOAA Tide Predictions allows users of the Tides and Currents website ( to generate tide predictions for up to 2 years in the past or future, at any of 3000+ locations around the United States.

What is the most powerful current in the world? ›

The Antarctic Circumpolar Current is the planet's most powerful and arguably most important current. It is the only current to flow clear around the globe without being diverted by any landmass.

Which river has most current? ›

List of rivers by discharge
1South AmericaAmazon
2AfricaCongo (Zaire)
48 more rows

What river has the strongest current in the world? ›

Amazon River - The Most Powerful River on Earth.

How many types of tide gauges are there? ›

Tide gauges are classified into two main types as follows : Non-recording type tide gauges. Recording type tide gauges.

What instrument is used to measure tides? ›

A tide gauge, which is one component of a modern water level monitoring station, is fitted with sensors that continuously record the height of the surrounding water level. This data is critical for many coastal activities, including safe navigation, sound engineering, and habitat restoration and preservation.

How much does a tide gauge cost? ›

The total cost per gauge, for a reasonable number of gauges, is estimated to be roughly $1500.

Is current stronger in shallow or deep water? ›

Tidal currents are strongest in large water depths away from the coastline and in straits where the current is forced into a narrow area. The most important tidal currents in relation to coastal morphology are the currents generated in tidal inlets.

What are the 5 major ocean currents? ›

There are five major gyres: the North Atlantic, the South Atlantic, the North Pacific, the South Pacific and the Indian Ocean Gyre, see figure 1. The Antarctic Circumpolar Current is situated in the Southern Ocean and constantly circles around Antarctica because there are no land masses to interrupt the currents.

What is high tide called? ›

This is called the tidal current. The incoming tide along the coast and into the bays and estuaries is called a flood current; the outgoing tide is called an ebb current.

Which tide occurs twice a day? ›

High tides occur about twice a day, about every 12 hours and 25 minutes. The reason is that the Moon takes 24 hours and 50 minutes to rotate once around the Earth so the Moon is over the same location 24 hours and 50 minutes later. Since high tides occur twice a day, one arrives each 12 hours and 25 minutes.

What are the 3 causes of tides? ›

The tides--the daily rise and fall of the sea's edge--are caused by the gravitational forces between the earth, the moon and the sun.

How long is a tidal day? ›

Because the Earth rotates through two tidal “bulges” every lunar day, coastal areas experience two high and two low tides every 24 hours and 50 minutes. High tides occur 12 hours and 25 minutes apart.

What is the best low tide? ›

The best low tides are negative low tides. During the spring the negative low tides are usually in the early morning whereas in the late fall and winter the negative low tides are in the afternoon.

Does high tide mean the water is in or out? ›

High and low tides refer to the regular rise and fall of the ocean's waters. High tide is when water covers much of the shore after rising to its highest level. Low tide is when the water retreats to its lowest level, moving away from the shore.

What is the height of water during low tide? ›

The typical tidal range in the open ocean is about 0.6 metres (2 feet) (blue and green on the map on the right). Closer to the coast, this range is much greater. Coastal tidal ranges vary globally and can differ anywhere from near zero to over 16 m (52 ft).

Why doesn't the Gulf of Mexico have a tide? ›

Because of its narrow connection to the Atlantic Ocean, the Gulf experiences very small tidal ranges.

What is the fastest tide in the world? ›

Are the Bay of Fundy tides a 50′ wall of water? The Bay's tides officially measure over 15 m (50′ in height), but the incoming tide is not a 50′ wall of water. It takes 6 hours for the tides to change from low tide to high tide. That means it takes more than an hour for the tide to rise 10′ vertically.

Where are the biggest tides in the world? ›

Located in Canada, between the provinces of Nova Scotia and Brunswick, sits the Bay of Fundy, home to the world largest tidal variations.

Do fish bite when it is raining? ›

Fish do bite when it rains, but their activity is generally lower during rain. Rain both oxygenates and colors the water, which are two very positive aspects when it comes to fishing, but the fish seem to need time to adjust to the sudden shift. That is why you should focus on fishing right after a rainfall instead!

Can you catch fish in low tide? ›

“In reality, low tides can concentrate both baitfish and game fish. The less water we have to search, the less area for fish to hide in.”

Is fishing better when water is rising or falling? ›

As water levels rise, fish consistently move closer to the water's edge. This means that while you may want to fish deeper out in the lake, reservoir or river during the late summer and fall, you should spend much of your spring fishing closer to the banks.

What tide is best for boating? ›

The best time to dock is during a slack tide. The minimal water movement is ideal for boaters, as long as the winds are not too strong. A low tide may moor your boat before you have a chance to reach the correct docking area. A high tide also will prevent you from reaching the place where you need to dock.

How do you calculate tidal range? ›

The tidal range is the difference between the height of water at high tide and low tide. Corrected for Morgat, the values are : Low water: 1.50 - 0.10 = 1.40 m. High tide: 7.10 - 0.40 = 6.70 m.

What is zero on a tide chart? ›

The 0 is the tide chart datum, which represents the low astronomical mean water level. This just means that it's the typical low water level mark. Anything below 0 means that it's an abnormally low tide, and anything above 0 is how high above the average low tide the water level is at any given point in time.

What does the M mean in tide times? ›

These are the predicted water heights for each tide. For example "(5.3m)" would mean 5.3 metres over Chart Datum.

What 2 things cause the tide? ›

In 1687, Sir Isaac Newton explained that ocean tides result from the gravitational attraction of the sun and moon on the oceans of the earth (Sumich, J.L., 1996).

What of the three has the biggest affect on the ocean tides? ›

Tides and the Moon

While the Sun and the rotation of the Earth both have some tidal impact, the location of the Moon has the biggest affect on the tide. The gravity of the Moon causes a high tide both on the side of the Earth directly below the Moon (sublunar tide) and the opposite side of the Earth (antipodal).

What ocean is the strongest? ›

The world's strongest ocean current, the Antarctic Circumpolar Current, is speeding up, according to new research, mostly because of rising ocean temperatures. The ACC carries water around the globe, pushing more water than any other ocean current.

What is the fastest current in the ocean? ›

The Gulf Stream is the fastest ocean current in the world with peak velocities near 2m/s.

Where is the ocean current the strongest? ›

That's the conclusion of a study in the journal Nature Climate Change that finds “robust acceleration” in the Antarctic Circumpolar Current (ACC). The current, which circulates around Antarctica, is the planet's strongest, and the only one that isn't blocked by any land masses.

Which is the deepest river in the world? ›

In addition, the Congo River is the world's deepest recorded river at 720 feet (220 meters) deep in parts — too deep for light to penetrate, The New York Times reported. It's also the second-longest river in Africa, spanning a length of approximately 2,920 miles (4,700 kilometers), according to

Who is the largest river of world? ›

The longest river in the world, measured from its mouth to its most distant, year-round source, is likely the Amazon, which flows 4,345 miles from the Peruvian Andes through Brazil to the Atlantic Ocean.

What is the slowest moving river in the world? ›

James River (Dakotas)

What is the deadliest river in the United States? ›

Officials posted signage at the mouth of Kern Canyon warning people they could die in the river. Considered the deadliest river in the USA, 315 deaths have occurred since 1968, 96 of those since 2000.

How long would it take to boat down the Mississippi river? ›

How Long Does It Take To Travel The Mississippi River By Boat? The amount of time spent depends on the type of boat used. However, it can take as little as 14 days and up to 50 days. Non-power boats would take longer.

What is the most powerful river in the United States? ›

List of U.S. rivers by discharge
NoRiverAverage discharge (cfs)
1Mississippi River593,000
2Ohio River281,500
3Saint Lawrence River348,000 (275,000 at U.S.-Canada boundary)
4Columbia River273,000
51 more rows

Is there a tide clock app? ›

Tideclock provides you with an overview of the current local tides. It displays the hours until next high or low tide. We also provide a monthly colour coded tide table for easy reference. You can add multiple Tide Stations and quickly switch between them.

What is spring tide and neap tide? ›

Rather, the term is derived from the concept of the tide "springing forth." Spring tides occur twice each lunar month all year long without regard to the season. Neap tides, which also occur twice a month, happen when the sun and moon are at right angles to each other.

What is high tide? ›

High tide is when water advances to its furthest extent onto the shoreline. Low tide is when it recedes to its furthest extent. Some freshwater rivers and lakes can have tides, too. A high tide that is significantly higher than normal is called a king tide.

What are the types of tides? ›

Ans: There are five types of tides:
  • Semi-diurnal tides.
  • Diurnal tides.
  • Mixed tides.
  • Spring tides.
  • Neap tides.

Which tide chart is most accurate? ›

Online predictions are more accurate and up-to-date than what is provided in the annual printed tables. NOAA tide predictions are used by both commercial and recreational mariners for safe navigation.

Which tide app is best? ›

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How does a tide clock work? ›

There is one hand on the clock face, and along the left side it points to the number of hours "until" the (lunar) high tide. The right hand side of the clock is marked "hours until low tide" and has a count-down of hours from 5 to 1. The number pointed to by the hand gives the time "until" the (lunar) low tide.

What is a ebb tide? ›

ebb tide, seaward flow in estuaries or tidal rivers during a tidal phase of lowering water level. The reverse flow, occurring during rising tides, is called the flood tide.

Are tides higher during a full moon? ›

To find out why the tide is higher when there's a full moon, we went to University of Delaware professor of physics and astronomy, Harry Shipman, who explained: "Tides are higher when the moon is full because at that time the gravity from the moon and sun are pulling together on the earth.

What are very low tides called? ›

When the sun, moon, and Earth are in alignment (at the time of the new or full moon), the solar tide has an additive effect on the lunar tide, creating extra-high high tides, and very low, low tides—both commonly called spring tides.

Does the moon affect the water in our body? ›

All of these forces are a lot stronger than the very small force of the moon's gravitational pull, so the water in our body responds to them but is hardly affected by the moon. The existence of all these other forces are the second reason that the moon doesn't affect the water in your body very much.

Why do we have 2 tides a day? ›

Because the Earth rotates through two tidal “bulges” every lunar day, coastal areas experience two high and two low tides every 24 hours and 50 minutes. High tides occur 12 hours and 25 minutes apart.

Why are tides 12 hours apart? ›

On average, high tides occur 12 hours 24 minutes apart. The 12 hours is due to the Earth's rotation, and the 24 minutes to the Moon's orbit. This is the "principal lunar semi-diurnal" period, abbreviated as the M2 tidal component, and it is, on average, half the time separating one lunar zenith from the next.

What is the highest tide called? ›

The term king tide is generally used to describe the highest tides of the year. Tides are caused by the gravitational forces of the moon and the sun.

What are the 3 causes of tides? ›

The tides--the daily rise and fall of the sea's edge--are caused by the gravitational forces between the earth, the moon and the sun.

What is the most common tide? ›

Semi-diurnal Tide

This is the most common type of tidal pattern. You'll see semi-diurnal tides along the U.S. Atlantic coast.


1. datum part2
(San Francisco Estuary Institute - Aquatic Science Center)
2. How Do Tides Work?
(BrainStuff - HowStuffWorks)
3. TIde & Current for Coastal Bay Anglers
4. "Rip Currents: The Water Looked Safe"
(Coastal Studies Institute)
5. Talleres GOES-R y Geonetcast Americas
(Agencia Espacial Mexicana)
6. Intro. to Tides Lab - Oceanography - 12/15/20
(Lawrence Flint)
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