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St Mary's Sound wave buoy observations on Sat, Sep 13, 2025

Hourly readings from the St Mary's Sound wave buoy for Sat, Sep 13, 2025, 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 4.1 ft (10th–90th percentile 3.7–5.1 ft), while mean reported wave period; measurement type unavailable was 5.3 seconds (10th–90th percentile 5–6 seconds). Mean water temperature was 14.9°C (10th–90th percentile 14.8–15.2°C). All 192 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 the islands of St Mary's and St Agnes in the Isles of Scilly. The National Network first deployed its Datawell Directional WaveRider in May 2014 to measure the exposed nearshore wave climate around the archipelago. The station reports wave height, period and direction together with sea temperature.

Metrics are rows; hours run left to right. Times use your device time zone.
St Mary's Sound wave buoy hourly observations Sat, Sep 13, 2025Last observation shown
Metric
Wave height (ft)665544344444455555444556555544444444444444444444
Observed period(s)6Reported6Reported6Reported6Reported5Reported5Reported5Reported5Reported4Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported6Reported6Reported6Reported6Reported6Reported6Reported6Reported6Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported6Reported
Wave power(kW/m)------------------------------------------------
Wave directionSWSWSWSWSWSSWSWSSWSWSSWSWSWSWSWSWWSWSWNWWSWNWSWNWSWSWWSWSWSWSWWSWWSWNSSWSSWSSWSSWSWSWSWWSWWSWSWWSWNWNWWSWSWWNWNW
Water temperature(°C)14.914.914.915.014.914.914.914.914.914.914.814.714.814.814.814.714.714.814.814.814.814.814.814.814.814.915.015.015.215.215.115.115.115.014.915.515.415.215.215.114.915.015.014.914.914.914.914.9

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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.

Which wave period is shown?

The table shows the best period measurement supplied for each observation. It is not necessarily the energy period used to calculate wave power.

Tp
Peak period: the period at the strongest spectral peak.
Tavg
The provider's average wave period.
Tm02
A mean period calculated from the wave spectrum.
Tz
Mean zero-crossing period.
Reported
A legacy value whose period type was not recorded.
Mixed
A daily or monthly mean containing more than one period type.

Wave power needs a genuine energy period (Te). SurfHog does not substitute Tp, Tavg, Tm02 or Tz when Te is missing.

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.

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