Skip to content
Surfhog home
Menu

Sevenstones wave buoy monthly means for 2018

Monthly means from the Sevenstones wave buoy for 2018, including available wave height, period, direction, wind and sea temperature data.

Last observation shown

Data available:  to 

Latest

Period Summary

Programmatically generated summary. Hog Says

8,719 wave-buoy observations covered all 365 days. Typical wave height was 5.9 ft (10th–90th percentile 2.3–12.1 ft), while the reported wave period averaged 8.4 seconds (10th–90th percentile 7–10 seconds). Typical wind was 18.3 mph (10th–90th percentile 9.2–33.3 mph) and mean water temperature was 12.9°C (10th–90th percentile 9.3–17.5°C). 40 of 43,595 checked values (0.1%) were excluded by quality control.

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

Typical Significant Wave Height

5.9ft
Mean: 6.7 ft
P10–P90: 2.3 — 12.1 ft
Recorded extremes

1 — 29.5 ft

Available for 8,695 of 8,719 hourly samples

Mean Observed Wave Period

8.4secs
P10–P90: 7 — 10secs
Recorded extremes

5 — 15secs

Available for 8,711 of 8,719 hourly samples

Typical Observed Wind

Variable, 18.3mph
Mean: 20.3 mph
P10–P90: 9.2 — 33.3 mph
Recorded extremes

2.2 — 58.8 mph

Circular concentration: 16%

Mean Water Temperature

12.9°C
P10–P90: 9.3 — 17.5°C
Recorded extremes

8.1 — 20.2°C

Available for 8,711 of 8,719 hourly samples

Chart showing grouped wave observations for Sevenstones. Use the table on this page for a text version of the same measurements. To open daily observations, use a linked month 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; months run left to right.
Sevenstones wave buoy monthly means 2018Last observation shown
Metric
Mean significant wave height (ft)1297754345699
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)998998878899
Mean peak wave direction------------
Mean wave direction------------
Mean directional spread (°)------------
Mean wind directionWconcentration 45%Variableconcentration 20%Variableconcentration 17%Variableconcentration 16%Variableconcentration 27%NNEconcentration 34%NWconcentration 34%Wconcentration 58%Variableconcentration 19%Variableconcentration 17%SSEconcentration 46%SWconcentration 57%
Mean wind speed (mph)292722191415131718192624
Mean water temperature(°C)10.69.68.910.011.614.918.117.515.513.812.611.6

Swipe sideways to see more months.

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.

› Wave Buoy List