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Belle-Île wave buoy daily means for Apr 2017

Daily means from the Belle-Île wave buoy for Apr 2017, 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

1,440 wave-buoy observations covered all 30 days. Typical wave height was 2.6 ft (10th–90th percentile 1.6–8.4 ft), while mean peak wave period was 9.3 seconds (10th–90th percentile 4.3–13.1 seconds). Typical calculated wave power was approximately 1.9 kW/m (10th–90th percentile 0.7–34.4 kW/m), derived from significant wave height and energy period. 16 of 4,320 checked values (0.4%) were excluded by quality control. Across 5 comparable years, mean wave height was below the same-month mean of 5.3 ft and mean wave period was below the same-month mean of 10.6 seconds.

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

Typical Significant Wave Height

2.6ft
Mean: 3.5 ft
P10–P90: 1.6 — 8.4 ft
Recorded extremes

1 — 11.7 ft

Mean Observed Wave Period

9.3secs
P10–P90: 4.3 — 13.1secs
Recorded extremes

2.5 — 25.8secs

Typical Wave Power

Approximately 1.87kW/m
Mean: 7.69kW/m
P10–P90: 0.7 — 34.37kW/m
Recorded extremes

0.25 — 57.11kW/m

Calculated from significant wave height and energy period.

Typical Observed Wind

-, -mph
Mean: - mph
P10–P90: - — - mph

Available for 0 of 720 hourly samples

Mean Water Temperature

-°C
P10–P90: - — -°C

Available for 0 of 720 hourly samples

Compared With Previous Aprils

Historical baseline from 7,200 observations across 5 years.

Wave Height
3.5ft
1.8ft below mean
Historical mean 5.348ft
Wave Period
9.3s
1.3s below mean
Historical mean 10.6s
Water Temperature
–
Not enough comparable data

Chart showing grouped wave observations for Belle-Île. 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 Belle-Île wave buoy

Belle-Île is a CANDHIS directional buoy south of Brittany, maintained through the Cerema-coordinated sea-state observatory and research partners. Its open Atlantic position represents conditions approaching Belle-Île and the sheltered-to-exposed transition along the Morbihan coast.

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

Metrics are rows; days run left to right.
Belle-Île wave buoy daily means Apr 2017Last observation shown
Metric
Mean significant wave height (ft)108598433343222322223222223223QC rejected
Mean maximum wave height (ft)16127141274446434344334543323433511
Mean peak period (s)11101314131212121111108998910845712989874510
Mean average period (s)9911121211101010987886665445755455458
Mean period Tm02 (s)778987667655564444344444444446
Mean peak wave directionWconcentration 100%Wconcentration 100%Wconcentration 99%Wconcentration 100%Wconcentration 100%Wconcentration 100%Wconcentration 100%Wconcentration 100%Wconcentration 100%Wconcentration 100%WNWconcentration 100%WNWconcentration 100%WNWconcentration 100%WNWconcentration 100%Wconcentration 99%Wconcentration 98%WNWconcentration 100%WNWconcentration 91%Econcentration 87%ESEconcentration 94%SSEconcentration 37%WNWconcentration 100%WNWconcentration 46%WNWconcentration 99%NWconcentration 69%WNWconcentration 91%WNWconcentration 94%WNWconcentration 99%Sconcentration 55%Wconcentration 94%
Mean directional spread (°)28.929.531.127.126.631.736.634.533.131.029.929.926.632.136.335.533.039.827.522.126.135.231.335.939.630.233.429.732.529.6
Mean water temperature(°C)------------------------------

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 Cerema CANDHIS coastal wave observatory.

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

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