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

Daily means from the St Mary's Sound wave buoy for Jun 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

1,440 wave-buoy observations covered all 30 days. Typical wave height was 2.3 ft (10th–90th percentile 1.1–5.1 ft), while mean average of more than one wave period type was 7.2 seconds (10th–90th percentile 4.8–10.6 seconds). Mean water temperature was 13.3°C (10th–90th percentile 12.8–13.9°C). 11 of 5,725 checked values (0.2%) were excluded by quality control. Across 3 comparable years, mean wave height was the same as the same-month mean of 2.8 ft and mean wave period was below the same-month mean of 7.8 seconds.

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

Typical Significant Wave Height

2.3ft
Mean: 2.8 ft
P10–P90: 1.1 — 5.1 ft
Recorded extremes

0.7 — 9.1 ft

Mean Observed Wave Period

7.2secs
P10–P90: 4.8 — 10.6secs
Recorded extremes

3.2 — 16.7secs

Available for 717 of 720 hourly samples

Observed Wave Direction

WSW

Circular concentration: 30%

Mean Water Temperature

13.3°C
P10–P90: 12.8 — 13.9°C
Recorded extremes

12.7 — 15.6°C

Compared With Previous Junes

Historical baseline from 2,160 observations across 3 years.

Wave Height
2.8ft
0ft above mean
Historical mean 2.789ft
Wave Period
7.2s
0.6s below mean
Historical mean 7.8s
Water Temperature
13.3°C
0.4°C below mean
Historical mean 13.7°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 Jun 2020Last observation shown
Metric
Mean significant wave height (ft)3123232112QC rejected4222211246533235433
Mean maximum wave height (ft)5234453222963333223610854359655
Mean peak period (s)6676777512977786667569781011107876
Mean zero-crossing period (s)444444445454454444446555645544
Mean energy period (s)------------------------------
Mean reported period (s)6677777711977786667569881011117876
Mean wave power, kilowatts per metre------------------------------
Mean peak wave directionESEconcentration 100%Variableconcentration 15%NEconcentration 45%NEconcentration 63%NWconcentration 72%NWconcentration 74%NNWconcentration 65%NNEconcentration 48%SWconcentration 55%WSWconcentration 79%Econcentration 57%Econcentration 99%SEconcentration 72%SSWconcentration 79%Sconcentration 94%SSWconcentration 98%WSWconcentration 82%NWconcentration 94%WSWconcentration 74%SWconcentration 78%SWconcentration 95%SWconcentration 84%WSWconcentration 72%WNWconcentration 71%NWconcentration 57%SWconcentration 75%SWconcentration 97%Wconcentration 82%Wconcentration 78%SWconcentration 99%
Mean directional spread (°)24.047.045.238.846.447.753.659.653.848.032.130.445.051.735.636.555.749.141.837.436.540.850.755.760.843.537.051.248.936.1
Mean reported wave directionESEconcentration 99%Variableconcentration 7%NEconcentration 56%NEconcentration 61%NWconcentration 72%NWconcentration 77%Nconcentration 57%Nconcentration 32%SSWconcentration 52%WSWconcentration 77%Econcentration 53%Econcentration 99%SEconcentration 80%Sconcentration 67%Sconcentration 87%SSWconcentration 97%WSWconcentration 77%NWconcentration 92%Wconcentration 75%SWconcentration 76%SWconcentration 91%SWconcentration 89%Wconcentration 69%WNWconcentration 54%NWconcentration 58%SWconcentration 65%SWconcentration 96%Wconcentration 79%Wconcentration 75%SWconcentration 99%
Mean water temperature(°C)13.813.813.313.513.112.912.913.012.912.812.813.113.413.113.213.513.513.313.113.213.013.413.313.513.713.313.213.513.813.9

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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.

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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