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Sevenstones wave buoy daily means for Jul 2011

Daily means from the Sevenstones wave buoy for Jul 2011, 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

734 wave-buoy observations covered all 31 days. Typical wave height was 3.6 ft (10th–90th percentile 1.6–7.9 ft), while the reported wave period averaged 7.6 seconds (10th–90th percentile 6–9 seconds). Typical wind was 15 mph (10th–90th percentile 6.9–28.9 mph) and mean water temperature was 15.5°C (10th–90th percentile 14.7–16.5°C). 1 of 3,670 checked values (0%) were excluded by quality control. Across 1 comparable year, mean wave height was below the same-month mean of 4.8 ft and mean wave period was above the same-month mean of 7.5 seconds.

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

Typical Significant Wave Height

3.6ft
Mean: 4.2 ft
P10–P90: 1.6 — 7.9 ft
Recorded extremes

1 — 15.1 ft

Available for 733 of 734 hourly samples

Mean Observed Wave Period

7.6secs
P10–P90: 6 — 9secs
Recorded extremes

5 — 13secs

Typical Observed Wind

NW, 15mph
Mean: 16.7 mph
P10–P90: 6.9 — 28.9 mph
Recorded extremes

2.2 — 42.6 mph

Circular concentration: 50%

Mean Water Temperature

15.5°C
P10–P90: 14.7 — 16.5°C
Recorded extremes

14 — 17.5°C

Compared With Previous Julys

Historical baseline from 680 observations across 1 year.

Wave Height
4.2ft
0.6ft below mean
Historical mean 4.8ft
Wave Period
7.6s
0.1s above mean
Historical mean 7.5s
Water Temperature
15.5°C
Not enough comparable data

Chart showing grouped wave observations for Sevenstones. 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 Sevenstones wave buoy

Sevenstones Lightship (WMO 62107) is a UK Met Office station west of Land's End, near the Seven Stones reef in the Western Approaches. Its exposed offshore position shows Atlantic systems before they reach Cornwall and the western English Channel and provides context for a notoriously hazardous shipping area.

Its current data source reports wave height, wave period, wave direction, directional spread, wind conditions, sea temperature, separate swell and wind-sea components and wave spectra.

Metrics are rows; days run left to right.
Sevenstones wave buoy daily means Jul 2011Last observation shown
Metric
Mean significant wave height (ft)234448107422124461386443223433522
Mean maximum wave height (ft)-------------------------------
Mean maximum crest height (ft)-------------------------------
Mean maximum trough height (ft)-------------------------------
Mean peak period (s)-------------------------------
Mean average period (s)-------------------------------
Mean period Tm02 (s)-------------------------------
Mean zero-crossing period (s)-------------------------------
Mean maximum wave period (s)-------------------------------
Mean reported period (s)69986897667681197987777777789886
Mean peak wave direction-------------------------------
Mean wave direction-------------------------------
Mean directional spread (°)-------------------------------
Mean wind directionNNWconcentration 93%Econcentration 81%ENEconcentration 91%SEconcentration 83%SSWconcentration 90%WSWconcentration 97%WSWconcentration 95%WSWconcentration 97%Wconcentration 98%WNWconcentration 92%NNWconcentration 95%NNEconcentration 96%Nconcentration 98%NWconcentration 79%SWconcentration 89%Wconcentration 90%WNWconcentration 97%WNWconcentration 95%NWconcentration 96%Nconcentration 35%NNWconcentration 97%Nconcentration 95%WNWconcentration 95%WNWconcentration 92%NWconcentration 95%NNWconcentration 96%NWconcentration 96%NNWconcentration 96%Nconcentration 98%WNWconcentration 32%SSWconcentration 94%
Mean wind speed (mph)8108141929242619161015128152837282717171915121113111019614
Mean water temperature(°C)15.215.515.715.615.215.014.814.815.115.616.016.016.016.316.115.714.914.814.614.714.814.815.015.415.415.416.216.616.216.416.1

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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 Met Office Marine observations.

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

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