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Bracklesham Bay wave buoy daily means for Dec 2020

Daily means from the Bracklesham Bay wave buoy for Dec 2020, 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 3.2 ft (10th–90th percentile 1–6.2 ft), while mean average of more than one wave period type was 7.9 seconds (10th–90th percentile 4–12.6 seconds). Mean water temperature was 9.5°C (10th–90th percentile 8.5–10.3°C). 10 of 5,863 checked values (0.2%) were excluded by quality control. Across 10 comparable years, mean wave height was below the same-month mean of 3.6 ft and mean wave period was below the same-month mean of 8.4 seconds.

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

Typical Significant Wave Height

3.2ft
Mean: 3.5 ft
P10–P90: 1 — 6.2 ft
Recorded extremes

0.5 — 12.3 ft

Available for 743 of 744 hourly samples

Mean Observed Wave Period

7.9secs
P10–P90: 4 — 12.6secs
Recorded extremes

1.7 — 20secs

Available for 741 of 744 hourly samples

Observed Wave Direction

SSW

Circular concentration: 93%

Mean Water Temperature

9.5°C
P10–P90: 8.5 — 10.3°C
Recorded extremes

7.4 — 11.3°C

Available for 743 of 744 hourly samples

Compared With Previous Decembers

Historical baseline from 14,570 observations across 10 years.

Wave Height
3.5ft
0.1ft below mean
Historical mean 3.642ft
Wave Period
7.9s
0.5s below mean
Historical mean 8.4s
Water Temperature
9.5°C
0.6°C above mean
Historical mean 8.9°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 Dec 2020Last observation shown
Metric
Mean significant wave height (ft)11QC rejected3QC rejected11124344545466554531484221
Mean maximum wave height (ft)216572123656786751098977427115322
Mean peak period (s)556876711566138912767912899114511121078
Mean zero-crossing period (s)3344434544555555455555543465544
Mean energy period (s)-------------------------------
Mean wave power, kilowatts per metre-------------------------------
Mean peak wave directionWSWconcentration 83%SWconcentration 88%SWconcentration 94%SSWconcentration 96%SSWconcentration 97%SSEconcentration 93%SSWconcentration 92%SSWconcentration 97%SWconcentration 96%Sconcentration 99%SSWconcentration 99%SSWconcentration 99%SSWconcentration 100%SSWconcentration 99%SSWconcentration 99%SSWconcentration 99%SSWconcentration 100%SSWconcentration 100%SSWconcentration 99%SSWconcentration 99%SSWconcentration 99%SSWconcentration 99%SSWconcentration 100%SSWconcentration 92%Wconcentration 90%SWconcentration 96%SSWconcentration 100%SSWconcentration 99%SSWconcentration 99%SSWconcentration 99%SSWconcentration 100%
Mean directional spread (°)24.228.820.923.324.030.726.923.820.124.621.022.321.321.123.722.220.520.620.521.220.920.920.322.920.519.917.821.422.023.727.0
Mean water temperature(°C)10.810.510.510.19.99.59.08.98.79.19.09.09.29.89.99.99.910.010.19.99.910.110.310.09.49.19.08.88.58.28.1

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.

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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