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Greenwich wave buoy daily means for Jul 2019

Daily means from the Greenwich wave buoy for Jul 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

743 wave-buoy observations covered all 31 days. Typical wave height was 1 ft (10th–90th percentile 0.3–2.6 ft), while mean reported wave period; measurement type unavailable was 6.5 seconds (10th–90th percentile 4–8 seconds). Typical wind was 12.8 mph (10th–90th percentile 5.8–21.9 mph) and mean water temperature was 16.2°C (10th–90th percentile 15.1–17.2°C). 12 of 3,715 checked values (0.3%) were excluded by quality control. Across 8 comparable years, mean wave height was the same as the same-month mean of 1.4 ft and mean wave period was above the same-month mean of 6.1 seconds.

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

Typical Wave Height

1ft
Mean: 1.4 ft
P10–P90: 0.3 — 2.6 ft
Recorded extremes

0 — 8.9 ft

Mean Wave Period

6.5secs
P10–P90: 4 — 8secs
Recorded extremes

3 — 26secs

Available for 731 of 743 hourly samples

Mean Water Temperature

16.2°C
P10–P90: 15.1 — 17.2°C
Recorded extremes

14.6 — 18.2°C

Typical Wind

Variable, 12.8mph
Mean: 13.7 mph
P10–P90: 5.8 — 21.9 mph
Recorded extremes

2.2 — 42.5 mph

Circular concentration: 19%

Compared With Previous Julys

Historical baseline from 5,728 observations across 8 years.

Wave Height
1.4ft
In line with the historical mean
Historical mean 1.4ft
Wave Period
6.5s
0.4s above mean
Historical mean 6.1s
Water Temperature
16.2°C
0.4°C above mean
Historical mean 15.8°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 2019Last observation shown
Metric
Mean wave height (ft)1111001111111111121221122332155
Mean observed period(s)5Reported5Reported4Reported4ReportedQC rejectedQC rejected8Reported5Reported5Reported5Reported5Reported5Reported5Reported6Reported5Reported6Reported8Reported5Reported6Reported6Reported6Reported6Reported7Reported8Reported8Reported9Reported8Reported6Reported6Reported7Reported6Reported
Mean wave power(kW/m)-------------------------------
Mean wind directionWconcentration 92%Nconcentration 84%NEconcentration 95%NEconcentration 96%NWconcentration 58%WNWconcentration 86%ENEconcentration 93%Econcentration 94%SSEconcentration 49%SWconcentration 89%WSWconcentration 94%Wconcentration 93%NWconcentration 61%NEconcentration 96%NEconcentration 91%NEconcentration 75%WSWconcentration 47%WSWconcentration 94%SSWconcentration 88%SWconcentration 91%WSWconcentration 81%SWconcentration 82%ENEconcentration 91%WSWconcentration 55%ENEconcentration 64%Wconcentration 89%WNWconcentration 92%WNWconcentration 86%SEconcentration 46%SSWconcentration 89%WSWconcentration 98%
Mean wind speed (mph)179171369141298111691112892015201110131514151421143026
Mean water temperature(°C)14.915.315.015.115.615.615.315.515.916.015.915.816.316.316.016.316.216.116.116.216.516.816.817.117.517.217.117.117.317.117.0

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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