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Les Pierres Noires wave buoy daily means for May 2025

Daily means from the Les Pierres Noires wave buoy for May 2025, 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 2.8 ft (10th–90th percentile 1.8–6.5 ft), while mean peak wave period was 10.1 seconds (10th–90th percentile 8.6–12.5 seconds). Typical calculated wave power was approximately 3.1 kW/m (10th–90th percentile 0.9–17 kW/m), derived from significant wave height and energy period. 16 of 4,464 checked values (0.4%) were excluded by quality control. Across 15 comparable years, mean wave height was below the same-month mean of 4.9 ft and mean wave period was above the same-month mean of 9.7 seconds.

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

Typical Significant Wave Height

2.8ft
Mean: 3.6 ft
P10–P90: 1.8 — 6.5 ft
Recorded extremes

1 — 12.3 ft

Mean Observed Wave Period

10.1secs
P10–P90: 8.6 — 12.5secs
Recorded extremes

2.4 — 17.4secs

Available for 742 of 744 hourly samples

Typical Wave Power

Approximately 3.07kW/m
Mean: 6.69kW/m
P10–P90: 0.89 — 16.96kW/m
Recorded extremes

0.33 — 66.13kW/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 Mays

Historical baseline from 22,207 observations across 15 years.

Wave Height
3.6ft
1.3ft below mean
Historical mean 4.856ft
Wave Period
10.1s
0.4s above mean
Historical mean 9.7s
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 May 2025Last observation shown
Metric
Mean significant wave height (ft)34332222234542223323332378107554
Mean maximum wave height (ft)47443333347764334444553411131511786
Mean peak period (s)121311991110710111313101081211111111109879111010999
Mean average period (s)10119655645101211896510961097658999899
Mean period Tm02 (s)67644443471086744764775546777677
Mean peak wave directionWNWconcentration 99%WNWconcentration 100%WNWconcentration 100%WNWconcentration 82%WNWconcentration 87%Wconcentration 93%WNWconcentration 100%NWconcentration 72%WNWconcentration 89%Wconcentration 100%WNWconcentration 100%WNWconcentration 100%WNWconcentration 100%WNWconcentration 99%WNWconcentration 92%WNWconcentration 86%Wconcentration 100%Wconcentration 100%Wconcentration 99%Wconcentration 100%Wconcentration 100%Wconcentration 100%Wconcentration 99%Wconcentration 98%Wconcentration 99%Wconcentration 100%WNWconcentration 99%WNWconcentration 100%Wconcentration 100%Wconcentration 100%Wconcentration 100%
Mean directional spread (°)29.224.828.235.232.634.729.332.531.026.723.523.928.630.334.738.226.527.932.324.725.227.831.630.025.325.125.526.627.725.126.7
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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