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St Mary's Sound wave buoy daily means for Oct 2020

Daily means from the St Mary's Sound wave buoy for Oct 2020, including available wave height, period, direction, wind and sea temperature data.

Last observation shown

Data available:  to 

Monthly means for

Latest

Period Summary

Programmatically generated summary. Hog Says

1,481 wave-buoy observations covered all 31 days. Typical wave height was 4.4 ft (10th–90th percentile 2.3–8.3 ft), while mean average of more than one wave period type was 7.8 seconds (10th–90th percentile 5.9–10.1 seconds). Typical wind was 0 mph and mean water temperature was 13.7°C (10th–90th percentile 13.1–14.1°C). 2 of 6,139 checked values (0%) were excluded by quality control. Across 4 comparable years, mean wave height was above the same-month mean of 4.3 ft and mean wave period was below the same-month mean of 8.8 seconds.

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

Typical Significant Wave Height

4.4ft
Mean: 4.9 ft
P10–P90: 2.3 — 8.3 ft
Recorded extremes

1.1 — 15.6 ft

Mean Observed Wave Period

7.8secs
P10–P90: 5.9 — 10.1secs
Recorded extremes

2.7 — 15.4secs

Observed Wave Direction

SW

Circular concentration: 47%

Mean Water Temperature

13.7°C
P10–P90: 13.1 — 14.1°C
Recorded extremes

12.9 — 14.7°C

Available for 742 of 744 hourly samples

Compared With Previous Octobers

Historical baseline from 2,871 observations across 4 years.

Wave Height
4.9ft
0.6ft above mean
Historical mean 4.265ft
Wave Period
7.8s
1s below mean
Historical mean 8.8s
Water Temperature
13.7°C
0.4°C below mean
Historical mean 14.1°C

Chart showing grouped wave observations for St Mary's Sound. Use the table on this page for a text version of the same measurements. To open hourly observations, use a linked day name in the table.

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; days run left to right.
St Mary's Sound wave buoy daily means Oct 2020Last observation shown
Metric
Mean significant wave height (ft)45444444222234334571053488568779
Mean maximum wave height (ft)6777776743334655681115856121381012111115
Mean peak period (s)89889887997687755771010878101089879
Mean zero-crossing period (s)5555555544444454455666566556556
Mean energy period (s)-------------------------------
Mean reported period (s)--------------------00000000000
Mean wave power, kilowatts per metre-------------------------------
Mean peak wave directionSWconcentration 96%Variableconcentration 22%NNEconcentration 59%NNWconcentration 59%WNWconcentration 59%Wconcentration 82%WSWconcentration 71%WSWconcentration 91%WNWconcentration 91%WNWconcentration 89%NWconcentration 95%WSWconcentration 60%NNWconcentration 72%ENEconcentration 69%ESEconcentration 97%ESEconcentration 97%SSEconcentration 84%SSWconcentration 100%Sconcentration 98%SSWconcentration 95%SSWconcentration 99%SSWconcentration 100%SWconcentration 97%SSWconcentration 99%SSWconcentration 99%WSWconcentration 90%SWconcentration 99%SWconcentration 96%SWconcentration 92%SSWconcentration 99%SSWconcentration 99%
Mean directional spread (°)45.843.749.150.453.753.351.443.557.454.849.944.145.440.128.629.236.630.229.528.928.135.837.529.726.646.937.345.042.637.229.3
Mean reported wave direction-Variableconcentration 22%------------------SSWconcentration 99%SSWconcentration 99%SWconcentration 98%SSWconcentration 99%SSWconcentration 99%WSWconcentration 88%SWconcentration 99%SWconcentration 94%SWconcentration 86%SSWconcentration 99%SSWconcentration 99%
Mean water temperature(°C)14.614.414.214.014.014.114.114.014.013.913.913.913.813.813.713.713.613.513.513.513.513.413.413.413.313.213.213.113.113.113.1

Swipe sideways to see more days.

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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