Skip to content
Surfhog home
Menu

Greenwich wave buoy daily means for May 2013

Daily means from the Greenwich wave buoy for May 2013, 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

740 wave-buoy observations covered all 31 days. Typical wave height was 1.3 ft (10th–90th percentile 0.7–4.1 ft), while mean reported wave period; measurement type unavailable was 5.9 seconds (10th–90th percentile 5–7 seconds). Typical wind was 17.2 mph (10th–90th percentile 6.9–28.9 mph) and mean water temperature was 9.6°C (10th–90th percentile 8.7–10.3°C). 9 of 3,688 checked values (0.2%) were excluded by quality control. Across 2 comparable years, mean wave height was above the same-month mean of 1.8 ft and mean wave period was below the same-month mean of 6.1 seconds.

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

Typical Wave Height

1.3ft
Mean: 1.9 ft
P10–P90: 0.7 — 4.1 ft
Recorded extremes

0 — 12.5 ft

Available for 737 of 740 hourly samples

Mean Wave Period

5.9secs
P10–P90: 5 — 7secs
Recorded extremes

4 — 8secs

Available for 736 of 740 hourly samples

Mean Water Temperature

9.6°C
P10–P90: 8.7 — 10.3°C
Recorded extremes

7.9 — 12.1°C

Available for 728 of 740 hourly samples

Typical Wind

W, 17.2mph
Mean: 17.5 mph
P10–P90: 6.9 — 28.9 mph
Recorded extremes

0 — 41.4 mph

Circular concentration: 41%

Available for 738 of 740 hourly samples

Compared With Previous Mays

Historical baseline from 1,478 observations across 2 years.

Wave Height
1.9ft
0.1ft above mean
Historical mean 1.8ft
Wave Period
5.9s
0.2s below mean
Historical mean 6.1s
Water Temperature
9.6°C
2.1°C below mean
Historical mean 11.7°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 May 2013Last observation shown
Metric
Mean wave height (ft)2112211135444361111111231111211
Mean observed period(s)5Reported5Reported5Reported5Reported6Reported7Reported8Reported6Reported6Reported7Reported6Reported6Reported6Reported6Reported7Reported7Reported6Reported7Reported6Reported5Reported5Reported6Reported5Reported5Reported5Reported5Reported5Reported6Reported6Reported7Reported6Reported
Mean wave power(kW/m)-------------------------------
Mean wind directionNEconcentration 98%NEconcentration 90%WNWconcentration 81%WSWconcentration 95%Wconcentration 91%SWconcentration 57%Econcentration 88%SSWconcentration 71%SWconcentration 95%WSWconcentration 99%WSWconcentration 94%Wconcentration 92%WSWconcentration 99%SWconcentration 78%SWconcentration 94%Variableconcentration 30%ENEconcentration 96%WNWconcentration 55%NEconcentration 46%WNWconcentration 87%NNWconcentration 66%WNWconcentration 70%NWconcentration 93%NWconcentration 66%NNWconcentration 73%WNWconcentration 94%Sconcentration 64%WNWconcentration 40%Wconcentration 91%NNWconcentration 87%NWconcentration 83%
Mean wind speed (mph)21161324116111824282827302528816713151112242321181513121115
Mean water temperature(°C)8.58.58.88.79.09.59.49.29.19.29.39.49.59.59.510.39.910.410.110.010.09.99.89.79.910.010.210.010.210.210.4

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.

› Wave Buoy List