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Belle-Île wave buoy daily means for Apr 2021

Daily means from the Belle-Île wave buoy for Apr 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

1,440 wave-buoy observations covered all 30 days. Typical wave height was 2.5 ft (10th–90th percentile 1.5–3.6 ft), while mean peak wave period was 8.6 seconds (10th–90th percentile 4.2–12.2 seconds). Typical calculated wave power was approximately 1.5 kW/m (10th–90th percentile 0.7–6 kW/m), derived from significant wave height and energy period. 18 of 4,320 checked values (0.4%) were excluded by quality control. Across 9 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 10.5 seconds.

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

Typical Significant Wave Height

2.5ft
Mean: 2.7 ft
P10–P90: 1.5 — 3.6 ft
Recorded extremes

1.1 — 8.6 ft

Mean Observed Wave Period

8.6secs
P10–P90: 4.2 — 12.2secs
Recorded extremes

2.7 — 17secs

Available for 719 of 720 hourly samples

Typical Wave Power

Approximately 1.52kW/m
Mean: 3.12kW/m
P10–P90: 0.67 — 6.02kW/m
Recorded extremes

0.42 — 44.59kW/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 12,960 observations across 9 years.

Wave Height
2.7ft
2.6ft below mean
Historical mean 5.282ft
Wave Period
8.6s
1.9s below mean
Historical mean 10.5s
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 2021Last observation shown
Metric
Mean significant wave height (ft)433223222232232223333235632332
Mean maximum wave height (ft)644344332453343335555447943543
Mean peak period (s)1110412767686585581110111312119711131175910
Mean average period (s)105465565655744456111111106591154576
Mean period Tm02 (s)743444544445443448887446644454
Mean peak wave directionWconcentration 100%WNWconcentration 85%NNEconcentration 80%Wconcentration 98%WNWconcentration 98%NWconcentration 98%WNWconcentration 98%Sconcentration 35%SWconcentration 81%WSWconcentration 91%WNWconcentration 96%WNWconcentration 99%SEconcentration 53%ESEconcentration 94%Variableconcentration 10%Wconcentration 77%Wconcentration 100%Wconcentration 100%Wconcentration 100%Wconcentration 100%Wconcentration 100%WSWconcentration 64%Sconcentration 32%SWconcentration 52%WSWconcentration 100%Wconcentration 96%WNWconcentration 77%WNWconcentration 100%WNWconcentration 99%Wconcentration 100%
Mean directional spread (°)35.538.638.140.729.624.334.933.042.243.024.934.925.422.642.743.040.231.830.233.733.938.429.929.731.242.334.021.730.840.3
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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