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Greenwich wave buoy monthly means for 2017

Monthly means from the Greenwich wave buoy for 2017, 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

8,442 wave-buoy observations covered 357 of 365 days (98%). Typical wave height was 1.6 ft (10th–90th percentile 0.7–5.6 ft), while mean reported wave period; measurement type unavailable was 6.5 seconds (10th–90th percentile 5–8 seconds). Typical wind was 18.3 mph (10th–90th percentile 8.1–32.2 mph) and mean water temperature was 13.2°C (10th–90th percentile 9.4–17.2°C). 280 of 42,210 checked values (0.7%) were excluded by quality control.

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

Typical Wave Height

1.6ft
Mean: 2.5 ft
P10–P90: 0.7 — 5.6 ft
Recorded extremes

0 — 20 ft

Available for 8,395 of 8,442 hourly samples

Mean Wave Period

6.5secs
P10–P90: 5 — 8secs
Recorded extremes

3 — 26secs

Available for 8,213 of 8,442 hourly samples

Mean Water Temperature

13.2°C
P10–P90: 9.4 — 17.2°C
Recorded extremes

8.4 — 19.3°C

Available for 8,441 of 8,442 hourly samples

Typical Wind

W, 18.3mph
Mean: 19.8 mph
P10–P90: 8.1 — 32.2 mph
Recorded extremes

0 — 63.3 mph

Circular concentration: 31%

Available for 8,439 of 8,442 hourly samples

Chart showing grouped wave observations for Greenwich. 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 Greenwich wave buoy

Greenwich Lightship (WMO 62305) is a UK Met Office station in the southern North Sea on the Greenwich meridian. It monitors marine conditions between the Dover Strait and the Thames approaches. The station feed can include wind, wave height, pressure, visibility, and air and sea temperature.

Metrics are rows; months run left to right.
Greenwich wave buoy monthly means 2017Last observation shown
Metric
Mean wave height (ft)233122223334
Mean observed period(s)6Reported7Reported7Reported7Reported7Reported7Reported6Reported6Reported7Reported7Reported6Reported6Reported
Mean wave power(kW/m)------------
Mean wind directionVariableconcentration 3%Variableconcentration 26%Variableconcentration 29%Variableconcentration 22%Variableconcentration 4%WSWconcentration 31%WSWconcentration 50%Wconcentration 38%WSWconcentration 40%WSWconcentration 61%WNWconcentration 52%WNWconcentration 61%
Mean wind speed (mph)202323151718181619222226
Mean water temperature(°C)9.99.29.710.812.014.516.417.317.216.313.911.3

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.

Which wave period is shown?

The table shows the best period measurement supplied for each observation. It is not necessarily the energy period used to calculate wave power.

Tp
Peak period: the period at the strongest spectral peak.
Tavg
The provider's average wave period.
Tm02
A mean period calculated from the wave spectrum.
Tz
Mean zero-crossing period.
Reported
A legacy value whose period type was not recorded.
Mixed
A daily or monthly mean containing more than one period type.

Wave power needs a genuine energy period (Te). SurfHog does not substitute Tp, Tavg, Tm02 or Tz when Te is missing.

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.

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