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Les Pierres Noires wave buoy daily means for Apr 2021

Daily means from the Les Pierres Noires 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 2.6 ft (10th–90th percentile 1.6–4.6 ft), while mean peak wave period was 9.3 seconds (10th–90th percentile 4–12.7 seconds). Typical calculated wave power was approximately 1.8 kW/m (10th–90th percentile 0.8–10.1 kW/m), derived from significant wave height and energy period. 22 of 4,320 checked values (0.5%) were excluded by quality control. Across 11 comparable years, mean wave height was below the same-month mean of 5.5 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: 2.9 ft
P10–P90: 1.6 — 4.6 ft
Recorded extremes

1.1 — 9.2 ft

Mean Observed Wave Period

9.3secs
P10–P90: 4 — 12.7secs
Recorded extremes

2.7 — 18.8secs

Available for 717 of 720 hourly samples

Typical Wave Power

Approximately 1.78kW/m
Mean: 3.97kW/m
P10–P90: 0.75 — 10.11kW/m
Recorded extremes

0.34 — 51.77kW/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 14,709 observations across 11 years.

Wave Height
2.9ft
2.6ft below mean
Historical mean 5.545ft
Wave Period
9.3s
1.3s below mean
Historical mean 10.6s
Water Temperature
–
Not enough comparable data

Chart showing grouped wave observations for Les Pierres Noires. 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 Les Pierres Noires wave buoy

Les Pierres Noires is a CANDHIS directional buoy west of Brittany, maintained through the French national sea-state observatory and its scientific and maritime partners. Its position near the offshore reef and lighthouse represents fully exposed Atlantic conditions approaching the Iroise Sea and western Brittany.

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

Metrics are rows; days run left to right.
Les Pierres Noires wave buoy daily means Apr 2021Last observation shown
Metric
Mean significant wave height (ft)433233322232222225544235632322
Mean maximum wave height (ft)644355432354343338876348952443
Mean peak period (s)11871286788108855810101313121110914139981010
Mean average period (s)1054655667667544571212111066101055677
Mean period Tm02 (s)844444545455444459988447644455
Mean peak wave directionWconcentration 99%NWconcentration 48%Nconcentration 42%Wconcentration 100%WNWconcentration 96%NWconcentration 99%WNWconcentration 94%Wconcentration 92%WSWconcentration 94%Wconcentration 95%WNWconcentration 97%WNWconcentration 98%SSWconcentration 32%SEconcentration 73%Variableconcentration 22%WSWconcentration 77%Wconcentration 99%WNWconcentration 99%WNWconcentration 100%WNWconcentration 100%Wconcentration 100%Wconcentration 91%SWconcentration 63%WSWconcentration 99%WSWconcentration 100%WNWconcentration 51%WNWconcentration 78%WNWconcentration 97%Wconcentration 99%Wconcentration 99%
Mean directional spread (°)30.435.035.533.026.126.530.636.842.735.528.633.433.531.932.631.929.022.521.124.529.736.328.826.926.836.736.931.131.732.0
Mean water temperature(°C)------------------------------

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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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