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Belle-Île wave buoy daily means for Jul 2021

Daily means from the Belle-Île 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

1,488 wave-buoy observations covered all 31 days. Typical wave height was 3.3 ft (10th–90th percentile 1.1–6.4 ft), while mean peak wave period was 7.9 seconds (10th–90th percentile 5–9.7 seconds). Typical calculated wave power was approximately 2.9 kW/m (10th–90th percentile 0.3–12.7 kW/m), derived from significant wave height and energy period. 4 of 4,464 checked values (0.1%) were excluded by quality control. Across 10 comparable years, mean wave height was below the same-month mean of 3.8 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

3.3ft
Mean: 3.7 ft
P10–P90: 1.1 — 6.4 ft
Recorded extremes

0.6 — 19.2 ft

Mean Observed Wave Period

7.9secs
P10–P90: 5 — 9.7secs
Recorded extremes

2.2 — 14.8secs

Typical Wave Power

Approximately 2.9kW/m
Mean: 6.54kW/m
P10–P90: 0.34 — 12.69kW/m
Recorded extremes

0.09 — 178kW/m

Calculated from significant wave height and energy period.

Typical Observed Wind

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

Available for 0 of 744 hourly samples

Mean Water Temperature

-°C
P10–P90: - — -°C

Available for 0 of 744 hourly samples

Compared With Previous Julys

Historical baseline from 14,857 observations across 10 years.

Wave Height
3.7ft
0.1ft below mean
Historical mean 3.773ft
Wave Period
7.9s
0.5s below mean
Historical mean 8.4s
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 Jul 2021Last observation shown
Metric
Mean significant wave height (ft)214671264343474322111113643354QC rejected4
Mean maximum wave height (ft)32681019974657106443222125974576117
Mean peak period (s)756881099879129889999877866557888
Mean average period (s)6467798776777668777554666556776
Mean period Tm02 (s)4445576654555456555444455445555
Mean peak wave directionWconcentration 100%WSWconcentration 92%WSWconcentration 96%WSWconcentration 100%WSWconcentration 99%Wconcentration 100%Wconcentration 100%Wconcentration 100%Wconcentration 100%Wconcentration 99%Wconcentration 100%Wconcentration 100%Wconcentration 100%Wconcentration 100%WNWconcentration 100%WNWconcentration 100%WNWconcentration 100%WNWconcentration 100%WNWconcentration 100%Wconcentration 99%Wconcentration 87%WSWconcentration 44%WSWconcentration 95%WSWconcentration 98%WSWconcentration 97%Wconcentration 99%Wconcentration 99%Wconcentration 100%WNWconcentration 100%Wconcentration 99%WNWconcentration 100%
Mean directional spread (°)33.436.633.832.635.229.232.329.533.731.431.231.729.031.631.128.832.234.333.339.841.136.435.934.835.533.733.628.426.426.529.2
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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