Live ocean buoy data, explained
An ocean buoy reports what is happening at sea right now: how big the waves are, how far apart they come, which way they travel, how hard the wind blows and how warm the water is. This page puts the latest report from every station in the NOAA National Data Buoy Center network on one map, with the units and the age of each reading, so you can read the sea the way a forecaster, surfer or sailor would.
What NDBC buoys are
The National Data Buoy Center (NDBC) is part of the US National Weather Service (NOAA). It operates moored weather buoys in the Atlantic, the Gulf of Mexico, the Pacific and around Alaska and Hawaii, plus coastal stations on piers, lighthouses and platforms, and it republishes data from partners such as the NOS water-level network, regional ocean observing systems (IOOS, including CDIP wave buoys) and international agencies. NDBC’s own station list, activestations.xml, had 1,354 entries on 11 October 2026. Not all of them send weather or wave data at any given moment, which is why this page does not quote a fixed number: the count at the top is computed from the file it just downloaded.
Station IDs follow a pattern. Five-digit IDs are buoys and offshore platforms, grouped by area (41xxx western Atlantic, 42xxx Gulf of Mexico, 44xxx northeast US coast, 46xxx eastern Pacific and Alaska, 51xxx Hawaii and the central Pacific). IDs with letters, such as AAMC1, are coastal and partner stations.
Significant wave height: what “2 m waves” means
Significant wave height (WVHT) is the average height, trough to crest, of the highest one third of the waves measured during a 20-minute sample. It is close to what an experienced observer would call “the wave height”. Many waves are smaller, and a few are bigger: over a few hours the single largest wave can be roughly twice the significant height. So a buoy reading of 2.0 m means most noticeable waves are around 2 m and the occasional set wave may approach 4 m.
Dominant vs average wave period
The dominant period (DPD) is the period, in seconds between crests, of the waves that carry the most energy. The average period (APD) is the mean period of all waves in the sample. When the two are close, one wave train dominates. When the dominant period is much longer than the average, a long-period swell from a distant storm is running underneath shorter local wind waves. Long periods carry much more energy for the same height: a 1.5 m swell at 15 seconds breaks far more powerfully on a beach than 1.5 m of 6-second wind chop. Surfers often use these rough labels, which the detail panel also shows:
| Dominant period | Usual label | What it means |
|---|
| under 8 s | wind swell | generated by local wind, short and choppy |
| 8–14 s | mixed / medium swell | a blend of local sea and swell from further away |
| 14 s and more | groundswell | from a distant storm, organised and powerful |
Wave direction (MWD) and wind direction (WDIR)
Both directions are in degrees true and both say where something comes from: an MWD of 270° means the dominant waves arrive from the west, and a WDIR of 45° is a northeasterly wind. The compass in the detail panel draws them as arrows pointing the way the waves and wind are travelling. When wind and waves come from very different directions, the sea is usually confused; when the wind blows against a strong current or swell, waves get steeper.
Wind speed and gusts
WSPD is the average wind speed over eight minutes on buoys and two minutes on land stations; GST is the highest 5- or 8-second gust within that period. NDBC reports both in metres per second; 1 m/s is 1.94 knots, 3.6 km/h or 2.24 mph. The detail panel also gives the Beaufort force using the WMO wind-speed bands (for example force 4 is 5.5–7.9 m/s, force 7 is 13.9–17.1 m/s, force 12 starts at 32.7 m/s).
Pressure and pressure tendency
PRES is the sea-level air pressure in hectopascals (the same as millibars). PTDY is the change over the three hours ending at the observation time, so -3.1 means the pressure fell 3.1 hPa in three hours. Falling pressure usually means a low-pressure system is approaching and wind will increase; the faster the fall, the stronger the change. Not every station reports PTDY, and the file only includes it when available.
Water temperature, air temperature and wetsuits
WTMP is the sea surface temperature, measured a little below the surface at the buoy. ATMP is the air temperature and DEWP the dew point, at the same height. Water near the shore can be several degrees colder than at an offshore buoy when upwelling brings cold water to the surface. For surfers, the detail panel turns WTMP into a rough wetsuit suggestion using these common bands (personal tolerance, wind and session length matter more than any table):
| Water temperature | Typical choice |
|---|
| 24 °C and warmer | boardshorts or swimsuit |
| 20–24 °C | 2 mm shorty or spring suit |
| 17–20 °C | 2/2 mm full suit |
| 14–17 °C | 3/2 mm full suit |
| 11–14 °C | 4/3 mm full suit |
| 7–11 °C | 5/4 mm full suit and boots |
| under 7 °C | 6/5 mm with boots, gloves and hood |
Units in the NDBC file
The page reads the column names and the units line at the top of latest_obs.txt, so values are always matched to the right column, and converts only for display.
| Column | Meaning | NDBC unit | Imperial view |
|---|
| WDIR / MWD | wind / wave direction (from) | degT | degT |
| WSPD / GST | wind speed / gust | m/s | m/s, kt, km/h or mph (your choice) |
| WVHT | significant wave height | m | ft |
| DPD / APD | dominant / average wave period | s | s |
| PRES / PTDY | pressure / 3-hour change | hPa | inHg |
| ATMP / WTMP / DEWP | air / water temperature, dew point | °C | °F |
| VIS | visibility | nmi | nmi (metric view: km) |
| TIDE | water level above mean lower low water | ft | ft (metric view: m) |
Why some values are missing
NDBC writes MM when a value is missing. Many stations measure only some things: tide gauges have no waves, wave buoys from partner networks often have no wind, and a sensor may be out of service. This page shows a missing value as “—” and greys out the dot when the coloured value is missing. Some partner buoys report wave height in 0.5 m steps with a period of 0; a period of 0 seconds is not physical, so the page treats it as missing. Values outside a plausible range (for example a water temperature above 40 °C) are also dropped.
How fresh is the data?
The file holds the latest observation per station. Most stations send a new observation every hour and some more often, so a value is typically between a few minutes and an hour old. The detail panel shows each observation time in UTC with its age, the tile Newest observation shows the most recent one, and the obs ≤ N h old filter hides stations that have gone quiet. The page re-downloads the file every 15 minutes and when you come back to the tab.
Data source, proxies and privacy
Observations come from https://www.ndbc.noaa.gov/data/latest_obs/latest_obs.txt and station names from activestations.xml. Browsers only allow a page to read another site’s file when that site permits it, so the page first asks NDBC directly and, if that is blocked, tries the public CORS proxies corsproxy.io, allorigins.win and codetabs.com in that order. The proxy that answers sees your IP address and that you asked for the NDBC file, nothing else. The last good copy is kept in your browser’s local storage, so the page can show it, clearly labelled with its age, if NDBC and the proxies are unreachable.
Near me uses your browser’s location permission. The coordinates stay inside the page, where they are only used to measure distances to stations; they are not sent to NDBC, the proxies or anyone else. The map background comes from Esri’s tile servers (which see which map area you view), the map library from cdnjs, the font from Google Fonts, and page views are counted with cookie-free Simple Analytics.
Limitations: observations, not forecasts
Everything here is a measurement that has already happened, at one point in the sea. Conditions at a beach depend on the coastline, the seabed, the tide and local wind, and can differ a lot from a buoy tens of kilometres offshore. Buoys sometimes break loose and drift, and sensors fail. Do not use this page for navigation or safety-of-life decisions; use official marine forecasts and warnings from your national weather service.
Share links
Every station has its own link: add ?station=46012 to the page address (or press Copy link in the detail panel). Add &var=wtmp to open the map coloured by water temperature; other values are wvht, wspd, pres and dpd. Units and the wind unit are remembered in your browser.
More ocean and earth tools