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Sevenstones wave buoy daily means for Sep 2020

Daily means from the Sevenstones wave buoy for Sep 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

713 wave-buoy observations covered all 30 days. Typical wave height was 4.6 ft (10th–90th percentile 2.6–6.9 ft), while the reported wave period averaged 8 seconds (10th–90th percentile 7–9 seconds). Typical wind was 16.1 mph (10th–90th percentile 9.2–28.7 mph) and mean water temperature was 15.8°C (10th–90th percentile 14.8–16.7°C). All 3,565 checked values passed quality control. Across 10 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: 4.9 ft
P10–P90: 2.6 — 6.9 ft
Recorded extremes

1.6 — 20.3 ft

Mean Observed Wave Period

8secs
P10–P90: 7 — 9secs
Recorded extremes

5 — 12secs

Typical Observed Wind

WNW, 16.1mph
Mean: 17.6 mph
P10–P90: 9.2 — 28.7 mph
Recorded extremes

2.2 — 51.9 mph

Circular concentration: 32%

Mean Water Temperature

15.8°C
P10–P90: 14.8 — 16.7°C
Recorded extremes

14.5 — 17.3°C

Compared With Previous Septembers

Historical baseline from 6,874 observations across 10 years.

Wave Height
4.9ft
0.4ft below mean
Historical mean 5.315ft
Wave Period
8s
0.2s above mean
Historical mean 7.8s
Water Temperature
15.8°C
0.2°C above mean
Historical mean 15.6°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 2020Last observation shown
Metric
Mean significant wave height (ft)3366543433466532455333513QC rejected55458
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)77898777778999886688101088988988
Mean peak wave direction------------------------------
Mean wave direction------------------------------
Mean directional spread (°)------------------------------
Mean wind directionSSEconcentration 96%SSWconcentration 95%WSWconcentration 93%Wconcentration 88%NWconcentration 94%WNWconcentration 95%Wconcentration 95%Wconcentration 98%NWconcentration 72%Nconcentration 67%WSWconcentration 95%WSWconcentration 90%Sconcentration 81%ESEconcentration 98%SSWconcentration 40%NNEconcentration 87%ENEconcentration 93%NEconcentration 94%NEconcentration 89%NNEconcentration 83%NNEconcentration 31%Wconcentration 66%Wconcentration 77%WNWconcentration 86%NNWconcentration 98%NNWconcentration 94%NNWconcentration 86%Wconcentration 81%Wconcentration 63%WSWconcentration 68%
Mean wind speed (mph)1320171319151516171017151517914242418147102040342118141327
Mean water temperature(°C)16.116.016.116.216.015.415.316.116.316.316.216.516.716.716.816.816.415.915.715.616.016.315.915.014.714.914.914.914.914.8

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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