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Penzance wave buoy daily means for Sep 2020

Daily means from the Penzance wave buoy for Sep 2020, 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

155 wave-buoy observations covered 7 of 30 days (23%). Typical wave height was 1.1 ft (10th–90th percentile 0.7–2.2 ft), while mean reported wave period; measurement type unavailable was 7.3 seconds (10th–90th percentile 4–11 seconds). Mean water temperature was 15.7°C (10th–90th percentile 15.5–16°C). 5 of 620 checked values (0.8%) were excluded by quality control. Across 9 comparable years, mean wave height was below the same-month mean of 1.7 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

1.1ft
Mean: 1.2 ft
P10–P90: 0.7 — 2.2 ft
Recorded extremes

0.6 — 2.9 ft

Mean Observed Wave Period

7.3secs
P10–P90: 4 — 11secs
Recorded extremes

3 — 13secs

Available for 150 of 155 hourly samples

Observed Wave Direction

S

Circular concentration: 99%

Mean Water Temperature

15.7°C
P10–P90: 15.5 — 16°C
Recorded extremes

15.4 — 16.2°C

Compared With Previous Septembers

Historical baseline from 6,413 observations across 9 years.

Wave Height
1.2ft
0.5ft below mean
Historical mean 1.7ft
Wave Period
7.3s
1.1s below mean
Historical mean 8.4s
Water Temperature
15.7°C
0.4°C above mean
Historical mean 15.3°C

Chart showing grouped wave observations for Penzance. 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 Penzance wave buoy

Penzance is a Datawell Directional WaveRider station in Mount's Bay off west Cornwall. First deployed by the National Network in April 2007, it records the comparatively sheltered wave climate on the bay's western side. Available observations include wave height, period and direction, sea temperature and calculated wave power.

Metrics are rows; days run left to right.
Penzance wave buoy daily means Sep 2020Last observation shown
Metric
Mean significant wave height (ft)1221111-----------------------
Mean observed period(s)5Reported4Reported5Reported8Reported11Reported9Reported9Reported-----------------------
Mean wave power, kilowatts per metre------------------------------
Mean wave directionSconcentration 97%Sconcentration 98%Sconcentration 100%Sconcentration 99%Sconcentration 99%Sconcentration 100%Sconcentration 100%-----------------------
Mean water temperature(°C)15.815.915.915.815.515.615.7-----------------------

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.

Which wave period is shown?

The table shows the best period measurement supplied for each observation. It is not necessarily the energy period used to calculate wave power.

Tp
Peak period: the period at the strongest spectral peak.
Tavg
The provider's average wave period.
Tm02
A mean period calculated from the wave spectrum.
Tz
Mean zero-crossing period.
Reported
A legacy value whose period type was not recorded.
Mixed
A daily or monthly mean containing more than one period type.

Wave power needs a genuine energy period (Te). SurfHog does not substitute Tp, Tavg, Tm02 or Tz when Te is missing.

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 Regional Coastal Monitoring Programme.

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