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St Mary's Sound wave buoy daily means for May 2026

Daily means from the St Mary's Sound wave buoy for May 2026, 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

1,477 wave-buoy observations covered all 31 days. Typical wave height was 2.1 ft (10th–90th percentile 1.2–4.4 ft), while the reported wave period averaged 4.6 seconds (10th–90th percentile 4–6 seconds). Mean water temperature was 12.7°C (10th–90th percentile 12.1–13.6°C). All 5,908 checked values passed quality control. Across 9 comparable years, mean wave height was below the same-month mean of 3 ft and mean wave period was below the same-month mean of 6.4 seconds.

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

Typical Significant Wave Height

2.1ft
Mean: 2.5 ft
P10–P90: 1.2 — 4.4 ft
Recorded extremes

0.9 — 9 ft

Mean Observed Wave Period

4.6secs
P10–P90: 4 — 6secs
Recorded extremes

3 — 7secs

Observed Wave Direction

WSW

Circular concentration: 34%

Mean Water Temperature

12.7°C
P10–P90: 12.1 — 13.6°C
Recorded extremes

11.8 — 15.6°C

Compared With Previous Mays

Historical baseline from 8,698 observations across 9 years.

Wave Height
2.5ft
0.5ft below mean
Historical mean 3ft
Wave Period
4.6s
1.8s below mean
Historical mean 6.4s
Water Temperature
12.7°C
0.6°C above mean
Historical mean 12.1°C

Chart showing grouped wave observations for St Mary's Sound. 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 St Mary's Sound wave buoy

St Mary's Sound station lies between St Mary's and St Agnes in the Isles of Scilly. The National Network first deployed a Datawell Directional WaveRider here in May 2014, establishing a nearshore record for an archipelago exposed to Atlantic swell and important to local navigation and coastal management.

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

Metrics are rows; days run left to right.
St Mary's Sound wave buoy daily means May 2026Last observation shown
Metric
Mean significant wave height (ft)2221111134323322347544322222223
Mean maximum wave height (ft)-------------------------------
Mean peak period (s)-------------------------------
Mean zero-crossing period (s)-------------------------------
Mean reported period (s)5455444444554454555555644544565
Mean peak wave direction-------------------------------
Mean directional spread (°)-------------------------------
Mean reported wave directionVariableconcentration 15%SWconcentration 55%WSWconcentration 72%Wconcentration 82%Variableconcentration 29%NNEconcentration 53%Wconcentration 53%Econcentration 54%ESEconcentration 99%Econcentration 99%ESEconcentration 82%SSWconcentration 96%NWconcentration 90%NNWconcentration 75%Nconcentration 52%WNWconcentration 63%WNWconcentration 87%WSWconcentration 54%SSWconcentration 99%SWconcentration 86%SSWconcentration 84%SWconcentration 95%WSWconcentration 94%Wconcentration 85%NNWconcentration 46%NNWconcentration 92%NWconcentration 67%SWconcentration 85%SSWconcentration 92%SWconcentration 88%WSWconcentration 89%
Mean water temperature(°C)11.911.912.012.312.112.212.512.413.012.912.812.612.612.612.512.412.412.412.412.512.512.612.813.013.313.613.813.513.913.913.7

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.

Observation data source

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

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