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Bracklesham Bay wave buoy daily means for Jul 2021

Daily means from the Bracklesham Bay wave buoy for Jul 2021, 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

1,486 wave-buoy observations covered all 31 days. Typical wave height was 1.1 ft (10th–90th percentile 0.4–3.8 ft), while mean average of more than one wave period type was 5.7 seconds (10th–90th percentile 2.9–9.1 seconds). Mean water temperature was 19°C (10th–90th percentile 17.6–20.8°C). 30 of 5,747 checked values (0.5%) were excluded by quality control. Across 11 comparable years, mean wave height was below the same-month mean of 1.9 ft and mean wave period was the same as the same-month mean of 5.7 seconds.

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

Typical Significant Wave Height

1.1ft
Mean: 1.7 ft
P10–P90: 0.4 — 3.8 ft
Recorded extremes

0.2 — 10 ft

Available for 738 of 744 hourly samples

Mean Observed Wave Period

5.7secs
P10–P90: 2.9 — 9.1secs
Recorded extremes

1.8 — 14.3secs

Available for 732 of 744 hourly samples

Observed Wave Direction

SSW

Circular concentration: 94%

Mean Water Temperature

19°C
P10–P90: 17.6 — 20.8°C
Recorded extremes

17 — 22°C

Available for 738 of 744 hourly samples

Compared With Previous Julys

Historical baseline from 15,975 observations across 11 years.

Wave Height
1.7ft
0.2ft below mean
Historical mean 1.87ft
Wave Period
5.7s
In line with the historical mean
Historical mean 5.7s
Water Temperature
19°C
0.3°C above mean
Historical mean 18.7°C

Chart showing grouped wave observations for Bracklesham Bay. 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 Bracklesham Bay wave buoy

Bracklesham Bay is a Channel Coastal Observatory National Network wave station off the West Sussex coast. Its nearshore position records conditions entering the broad bay between Selsey and Hayling Island, supporting coastal management along an exposed beach frontage west of Chichester Harbour.

Its current data source reports wave height, wave period, wave direction, directional spread, wave power and sea temperature.

Metrics are rows; days run left to right.
Bracklesham Bay wave buoy daily means Jul 2021Last observation shown
Metric
Mean significant wave height (ft)1113263221111111111001111124363
Mean maximum wave height (ft)1124495321122211111111221247594
Mean peak period (s)5436576658879755854554547646675
Mean zero-crossing period (s)3334454334434433333333333334454
Mean energy period (s)-------------------------------
Mean wave power, kilowatts per metre-------------------------------
Mean peak wave directionSSWconcentration 98%SWconcentration 92%SSWconcentration 93%SWconcentration 99%SSWconcentration 93%SSWconcentration 99%SWconcentration 99%SWconcentration 99%SWconcentration 99%SSWconcentration 99%SSWconcentration 100%SSWconcentration 95%SSWconcentration 97%SWconcentration 99%SWconcentration 89%SSWconcentration 99%SSWconcentration 99%SSWconcentration 97%SWconcentration 97%SSWconcentration 98%SSWconcentration 97%Sconcentration 88%SSEconcentration 84%Sconcentration 95%SSWconcentration 99%SWconcentration 99%SWconcentration 99%SWconcentration 100%SWconcentration 100%SSWconcentration 99%SWconcentration 99%
Mean directional spread (°)24.728.625.120.220.717.519.621.322.223.223.128.224.822.324.725.526.729.230.029.630.029.626.329.626.824.821.118.520.021.119.1
Mean water temperature(°C)17.618.018.018.018.017.617.517.617.818.118.117.918.118.418.518.619.219.820.320.721.121.120.720.420.320.120.019.819.319.018.7

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.

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 Regional Coastal Monitoring Programme.

Learn how SurfHog combines, checks and summarizes observations in the data and methodology notes.

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