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Greenwich wave buoy daily means for Jul 2018

Daily means from the Greenwich wave buoy for Jul 2018, 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

732 wave-buoy observations covered all 31 days. Typical wave height was 0.7 ft (10th–90th percentile 0.3–2 ft), while mean reported wave period; measurement type unavailable was 5.3 seconds (10th–90th percentile 4–7 seconds). Typical wind was 11.4 mph (10th–90th percentile 5.8–21.9 mph) and mean water temperature was 16.5°C (10th–90th percentile 15–18°C). 12 of 3,660 checked values (0.3%) were excluded by quality control. Across 7 comparable years, mean wave height was below the same-month mean of 1.4 ft and mean wave period was below the same-month mean of 6.2 seconds.

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

Typical Wave Height

0.7ft
Mean: 1 ft
P10–P90: 0.3 — 2 ft
Recorded extremes

0 — 6.2 ft

Mean Wave Period

5.3secs
P10–P90: 4 — 7secs
Recorded extremes

3 — 9secs

Available for 720 of 732 hourly samples

Mean Water Temperature

16.5°C
P10–P90: 15 — 18°C
Recorded extremes

14.4 — 19.9°C

Typical Wind

Variable, 11.4mph
Mean: 12.5 mph
P10–P90: 5.8 — 21.9 mph
Recorded extremes

2.2 — 36.9 mph

Circular concentration: 13%

Compared With Previous Julys

Historical baseline from 4,996 observations across 7 years.

Wave Height
1ft
0.4ft below mean
Historical mean 1.4ft
Wave Period
5.3s
0.9s below mean
Historical mean 6.2s
Water Temperature
16.5°C
0.8°C above mean
Historical mean 15.7°C

Chart showing grouped wave observations for Greenwich. 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 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; days run left to right.
Greenwich wave buoy daily means Jul 2018Last observation shown
Metric
Mean wave height (ft)1121111101111111111111100013532
Mean observed period(s)5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported5Reported6Reported5Reported5Reported4Reported5Reported5Reported6Reported7Reported6Reported6Reported5Reported5Reported5Reported5Reported4Reported5Reported7Reported7Reported7Reported7Reported7Reported
Mean wave power(kW/m)-------------------------------
Mean wind directionNEconcentration 98%NEconcentration 99%NEconcentration 97%ENEconcentration 75%Wconcentration 88%SWconcentration 91%WNWconcentration 78%Nconcentration 76%ENEconcentration 32%NEconcentration 42%NNEconcentration 58%NEconcentration 80%NEconcentration 94%NEconcentration 81%Wconcentration 42%Wconcentration 93%WSWconcentration 92%WSWconcentration 66%NEconcentration 91%Econcentration 87%Nconcentration 34%WSWconcentration 97%WSWconcentration 95%WSWconcentration 78%WNWconcentration 91%NEconcentration 59%Wconcentration 80%SWconcentration 80%Sconcentration 99%SSWconcentration 92%SWconcentration 78%
Mean wind speed (mph)20222210111299811991196121581310811131010111320271613
Mean water temperature(°C)14.714.814.815.215.515.616.417.317.616.416.215.915.916.116.316.216.116.716.516.316.916.917.017.418.118.418.517.317.017.117.1

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.

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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