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St Mary's Sound wave buoy observations on Wed, Dec 30, 2020

Hourly readings from the St Mary's Sound wave buoy for Wed, Dec 30, 2020, including available wave height, period, direction, wind and sea temperature data.

Last observation shown

Oldest observation available

Daily means for

Latest

Period Summary

Programmatically generated summary. Hog Says

48 wave-buoy observations were recorded during the day. Typical wave height was 3.1 ft (10th–90th percentile 2.8–3.5 ft), while mean peak wave period was 7.7 seconds (10th–90th percentile 6.4–9.2 seconds). Typical wind was 0 mph and mean water temperature was 10.9°C (10th–90th percentile 10.8–10.9°C). All 216 checked values passed quality control.

Generated only from the observations and comparisons shown on this page.

Line chart showing wave height, wave period and sea temperature for St Mary's Sound. Use the detailed observations table below for the same data in text form.

About St Mary's Sound wave buoy

St Mary's Sound station lies between St Mary's and St Agnes in the Isles of Scilly. The National Network first deployed a Datawell Directional WaveRider here in May 2014, establishing a nearshore record for an archipelago exposed to Atlantic swell and important to local navigation and coastal management.

Its current data source reports wave height, wave period, wave direction, directional spread, wave power and sea temperature.

Metrics are rows; hours run left to right. Times use your device time zone.
St Mary's Sound wave buoy hourly observations Wed, Dec 30, 2020Last observation shown
Metric
Significant wave height (ft)433333333333333333333333333333344333334433344333
Maximum wave height (ft)555555655464654445555544444455666544457655566544
Peak period (s)888108787781198101088117777766666677666878778888888109
Zero-crossing period (s)554455555555566665555554444444444455566765555544
Energy period (s)------------------------------------------------
Reported period (s)4-4-5-5-5-5-6-6-5-5-5-4-4-4-4-4-4-5-6-6-5-5-4-4-
Wave power, kilowatts per metre------------------------------------------------
Peak wave directionENENENENNWNENENNWNNWNWNNWNWNWWNWWSWWSWWSWWNWWSWWSWNEENEENEENENENNNWNNWWNWNWNWNWNWNWNWNWWSWWSWWSWWSWWSWSWWSWWSWWSWWNW
Directional spread (°)39.045.058.067.061.054.054.058.042.050.071.060.071.048.064.059.067.071.075.071.074.074.054.060.069.067.071.065.056.049.045.035.043.032.039.044.047.052.040.042.046.051.054.042.040.048.059.068.0
Reported wave directionNE-NNW-NE-NNW-NNW-NW-WSW-WSW-W-WSW-ENE-E-NE-NNW-WNW-NW-NW-NW-WSW-WSW-W-SW-WSW-WSW-
Water temperature(°C)10.910.910.910.910.910.910.910.910.910.910.910.910.810.910.810.810.810.910.911.011.011.010.910.910.910.910.910.910.910.910.910.910.910.910.910.910.810.810.910.810.810.910.910.910.910.910.910.9

Swipe sideways to see more hours.

Wave metric colour key

Colours move through the scale as each number increases. They do not by themselves mean that conditions are good, safe or suitable for you.

Wave & swell height0–40+ ft
Wave & swell period0–22+ s
Wind speed0–75 mph

The displayed numbers remain the source of truth; colour is an additional visual cue.

What does buoy wave power mean?

kW/m means kilowatts of wave power per metre of wave crest. It describes the rate at which the observed sea state carries energy past the buoy.

Unlike the shore-directed forecast value, buoy wave power is the total power at the observation point. It is not projected towards a particular beach and does not predict breaking wave height.

In deep water, wave power can be calculated with:

P is approximately 0.49 times significant wave height squared times wave energy period.

P is power in kW/m, Hs is significant wave height in metres, and Te is wave energy period in seconds.

  • Provider-reported power is used when available.
  • Otherwise, a value is calculated only when both significant height and a genuine energy period are available. The ≈ symbol marks calculated values.
  • A dash is shown instead of substituting peak, Tm02, zero-crossing or other period measurements.
  • Daily and monthly figures use the mean of hourly-normalized observation power values; they are not calculated from mean height and period.

Wave direction, spectrum, water depth and local bathymetry still matter. Wave power is best read alongside height, period and direction rather than as a standalone surf-quality score.

The observation data displayed on this page is from the Regional Coastal Monitoring Programme.

Learn how SurfHog combines, checks and summarizes observations in the data and methodology notes.

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