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Sevenstones wave buoy daily means for Sep 2015

Daily means from the Sevenstones wave buoy for Sep 2015, 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

696 wave-buoy observations covered all 30 days. Typical wave height was 3.6 ft (10th–90th percentile 1.6–6.9 ft), while the reported wave period averaged 6.8 seconds (10th–90th percentile 5–8.4 seconds). Typical wind was 18.3 mph (10th–90th percentile 10.3–27.7 mph) and mean water temperature was 14.6°C (10th–90th percentile 14.1–15.2°C). 50 of 2,845 checked values (1.8%) were excluded by quality control. Across 5 comparable years, mean wave height was below the same-month mean of 4.9 ft and mean wave period was below the same-month mean of 7.9 seconds.

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

Typical Significant Wave Height

3.6ft
Mean: 4 ft
P10–P90: 1.6 — 6.9 ft
Recorded extremes

0 — 13.5 ft

Available for 677 of 696 hourly samples

Mean Observed Wave Period

6.8secs
P10–P90: 5 — 8.4secs
Recorded extremes

5 — 11secs

Available for 667 of 696 hourly samples

Typical Observed Wind

Variable, 18.3mph
Mean: 18.9 mph
P10–P90: 10.3 — 27.7 mph
Recorded extremes

0 — 47.2 mph

Circular concentration: 18%

Available for 694 of 696 hourly samples

Mean Water Temperature

14.6°C
P10–P90: 14.1 — 15.2°C
Recorded extremes

13.7 — 15.5°C

Available for 61 of 696 hourly samples

Compared With Previous Septembers

Historical baseline from 3,333 observations across 5 years.

Wave Height
4ft
0.9ft below mean
Historical mean 4.9ft
Wave Period
6.8s
1.1s below mean
Historical mean 7.9s
Water Temperature
14.6°C
1.1°C below mean
Historical mean 15.7°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 2015Last observation shown
Metric
Mean significant wave height (ft)223332114556587445336855632334
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)555566557997788777778887986666
Mean peak wave direction------------------------------
Mean wave direction------------------------------
Mean directional spread (°)------------------------------
Mean wind directionNNWconcentration 98%NNWconcentration 92%NNWconcentration 95%Nconcentration 97%Nconcentration 91%NNEconcentration 99%NEconcentration 95%Econcentration 98%ESEconcentration 98%ESEconcentration 97%SSEconcentration 93%WSWconcentration 84%SEconcentration 84%WNWconcentration 70%Wconcentration 49%NNEconcentration 86%WSWconcentration 89%NWconcentration 91%WSWconcentration 72%SSWconcentration 93%WSWconcentration 83%NWconcentration 99%Wconcentration 90%Wconcentration 97%NWconcentration 79%Econcentration 94%Econcentration 97%Econcentration 96%Econcentration 92%ENEconcentration 94%
Mean wind speed (mph)14181717191814222623192324321823171671321251719101317242122
Mean water temperature(°C)15.014.514.2---------------------------

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 Met Office Marine observations.

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

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