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Sevenstones wave buoy daily means for Apr 2019

Daily means from the Sevenstones wave buoy for Apr 2019, 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

717 wave-buoy observations covered all 30 days. Typical wave height was 5.6 ft (10th–90th percentile 3.3–10 ft), while the reported wave period averaged 8.5 seconds (10th–90th percentile 7–11 seconds). Typical wind was 18.3 mph (10th–90th percentile 9.2–35 mph) and mean water temperature was 10.5°C (10th–90th percentile 10.1–11°C). All 3,585 checked values passed quality control. Across 9 comparable years, mean wave height was above the same-month mean of 5.5 ft and mean wave period was above the same-month mean of 8.2 seconds.

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

Typical Significant Wave Height

5.6ft
Mean: 6.2 ft
P10–P90: 3.3 — 10 ft
Recorded extremes

2 — 23.3 ft

Mean Observed Wave Period

8.5secs
P10–P90: 7 — 11secs
Recorded extremes

5 — 13secs

Typical Observed Wind

ESE, 18.3mph
Mean: 20.1 mph
P10–P90: 9.2 — 35 mph
Recorded extremes

2.2 — 43.8 mph

Circular concentration: 37%

Mean Water Temperature

10.5°C
P10–P90: 10.1 — 11°C
Recorded extremes

9.8 — 11.7°C

Compared With Previous Aprils

Historical baseline from 6,414 observations across 9 years.

Wave Height
6.2ft
0.7ft above mean
Historical mean 5.5ft
Wave Period
8.5s
0.3s above mean
Historical mean 8.2s
Water Temperature
10.5°C
0.3°C above mean
Historical mean 10.2°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 Apr 2019Last observation shown
Metric
Mean significant wave height (ft)35107674354656910745436457712QC rejected765
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)7787910779911107789878911109981010999
Mean peak wave direction------------------------------
Mean wave direction------------------------------
Mean directional spread (°)------------------------------
Mean wind directionESEconcentration 97%NWconcentration 90%NNWconcentration 94%WNWconcentration 80%ESEconcentration 80%Econcentration 80%ENEconcentration 74%SEconcentration 91%ENEconcentration 71%NEconcentration 92%Econcentration 78%ESEconcentration 96%ESEconcentration 99%SEconcentration 99%SEconcentration 99%SWconcentration 67%Econcentration 94%Econcentration 98%ENEconcentration 86%NNEconcentration 79%Econcentration 68%ESEconcentration 92%ESEconcentration 98%Sconcentration 86%SSWconcentration 70%WSWconcentration 86%WNWconcentration 99%Wconcentration 84%SSEconcentration 90%SSEconcentration 94%
Mean wind speed (mph)18263320161620171114131933363711232412912191920212933141113
Mean water temperature(°C)10.310.19.910.010.110.210.210.210.410.410.310.210.210.210.310.710.610.510.610.910.910.810.910.810.910.910.610.811.111.2

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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