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Sevenstones wave buoy daily means for Sep 2018

Daily means from the Sevenstones wave buoy for Sep 2018, 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

719 wave-buoy observations covered all 30 days. Typical wave height was 4.6 ft (10th–90th percentile 2.6–8.5 ft), while the reported wave period averaged 7.9 seconds (10th–90th percentile 6–10 seconds). Typical wind was 17.2 mph (10th–90th percentile 9.2–27.7 mph) and mean water temperature was 15.5°C (10th–90th percentile 14.4–16.6°C). All 3,595 checked values passed quality control. Across 8 comparable years, mean wave height was below the same-month mean of 5.3 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

4.6ft
Mean: 5 ft
P10–P90: 2.6 — 8.5 ft
Recorded extremes

1.3 — 15.1 ft

Mean Observed Wave Period

7.9secs
P10–P90: 6 — 10secs
Recorded extremes

6 — 15secs

Typical Observed Wind

Variable, 17.2mph
Mean: 18.1 mph
P10–P90: 9.2 — 27.7 mph
Recorded extremes

3.4 — 42.5 mph

Circular concentration: 19%

Mean Water Temperature

15.5°C
P10–P90: 14.4 — 16.6°C
Recorded extremes

13.9 — 17.6°C

Compared With Previous Septembers

Historical baseline from 5,436 observations across 8 years.

Wave Height
5ft
0.3ft below mean
Historical mean 5.3ft
Wave Period
7.9s
0.1s above mean
Historical mean 7.8s
Water Temperature
15.5°C
In line with the historical mean
Historical mean 15.5°C

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 Sep 2018Last observation shown
Metric
Mean significant wave height (ft)33554444666555434910119663244533
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)79877777898998867889877781210878
Mean peak wave direction------------------------------
Mean wave direction------------------------------
Mean directional spread (°)------------------------------
Mean wind directionSSEconcentration 97%SSEconcentration 64%Nconcentration 84%Nconcentration 100%Nconcentration 97%NWconcentration 98%WNWconcentration 93%SWconcentration 93%WSWconcentration 89%SWconcentration 92%Wconcentration 49%Nconcentration 96%WNWconcentration 92%Wconcentration 95%SSWconcentration 87%SSWconcentration 96%Sconcentration 94%SWconcentration 93%SWconcentration 90%SSWconcentration 89%WNWconcentration 96%WSWconcentration 39%Nconcentration 98%NEconcentration 84%SEconcentration 84%ESEconcentration 82%ENEconcentration 78%NNEconcentration 95%ENEconcentration 86%NNWconcentration 87%
Mean wind speed (mph)13101926222115171614171613171419222621293019261213914231318
Mean water temperature(°C)17.017.016.916.215.916.316.516.115.915.916.115.615.715.315.315.915.515.215.314.814.814.814.714.714.714.814.814.314.114.3

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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 Met Office Marine observations.

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

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