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St Mary's Sound wave buoy daily means for Jan 2023

Daily means from the St Mary's Sound wave buoy for Jan 2023, 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

1,070 wave-buoy observations covered 23 of 31 days (74%). Typical wave height was 6.3 ft (10th–90th percentile 3.6–10.2 ft), while mean average of more than one wave period type was 9.2 seconds (10th–90th percentile 6–11.5 seconds). Typical wind was 0 mph and mean water temperature was 11.1°C (10th–90th percentile 10.8–11.4°C). 4 of 4,728 checked values (0.1%) were excluded by quality control. Across 6 comparable years, mean wave height was above the same-month mean of 4.7 ft and mean wave period was above the same-month mean of 7.8 seconds.

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

Typical Significant Wave Height

6.3ft
Mean: 6.5 ft
P10–P90: 3.6 — 10.2 ft
Recorded extremes

0.3 — 14 ft

Mean Observed Wave Period

9.2secs
P10–P90: 6 — 11.5secs
Recorded extremes

3.9 — 14.3secs

Observed Wave Direction

SW

Circular concentration: 80%

Mean Water Temperature

11.1°C
P10–P90: 10.8 — 11.4°C
Recorded extremes

9.9 — 11.4°C

Compared With Previous Januarys

Historical baseline from 4,366 observations across 6 years.

Wave Height
6.5ft
1.8ft above mean
Historical mean 4.7ft
Wave Period
9.2s
1.4s above mean
Historical mean 7.8s
Water Temperature
11.1°C
0.3°C above mean
Historical mean 10.8°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 Jan 2023Last observation shown
Metric
Mean significant wave height (ft)1059768119QC rejected88979755434420--------
Mean maximum wave height (ft)15814111011171391313131015119775667---------
Mean peak period (s)1210998810101089999911111210965---------
Mean zero-crossing period (s)7666567666666666655544---------
Mean energy period (s)-------------------------------
Mean reported period (s)76665676666666666555466--------
Mean wave power, kilowatts per metre-------------------------------
Mean peak wave directionSSWconcentration 99%SWconcentration 100%SSWconcentration 99%SWconcentration 99%SWconcentration 93%SWconcentration 95%SSWconcentration 100%SWconcentration 98%WSWconcentration 89%SSWconcentration 99%SWconcentration 99%SWconcentration 100%SWconcentration 97%SSWconcentration 100%SWconcentration 98%WSWconcentration 93%Wconcentration 66%WNWconcentration 71%Wconcentration 80%WSWconcentration 90%Sconcentration 81%SSEconcentration 79%---------
Mean directional spread (°)25.634.929.438.340.137.426.839.253.033.535.836.245.532.145.648.754.960.856.152.541.243.3---------
Mean reported wave directionSSWconcentration 99%SWconcentration 99%SSWconcentration 99%SWconcentration 96%SWconcentration 91%SWconcentration 94%SSWconcentration 100%SWconcentration 97%WSWconcentration 84%SSWconcentration 99%SWconcentration 98%SWconcentration 100%SWconcentration 90%SWconcentration 99%SWconcentration 98%WSWconcentration 81%Wconcentration 62%WNWconcentration 50%Wconcentration 76%WSWconcentration 85%Sconcentration 71%Variableconcentration 14%NNWconcentration 72%--------
Mean water temperature(°C)11.411.311.311.411.411.411.411.311.311.311.311.311.311.211.211.110.910.810.810.810.810.510.3--------

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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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