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Chesil wave buoy daily means for Apr 2018

Daily means from the Chesil wave buoy for Apr 2018, 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

1,439 wave-buoy observations covered all 30 days. Typical wave height was 2.7 ft (10th–90th percentile 1.3–5.6 ft), while mean average of more than one wave period type was 9.9 seconds (10th–90th percentile 5–14.8 seconds). Mean water temperature was 9.1°C (10th–90th percentile 7.9–10.2°C). 15 of 5,690 checked values (0.3%) were excluded by quality control. Across 8 comparable years, mean wave height was above the same-month mean of 2.4 ft and mean wave period was above the same-month mean of 8.7 seconds.

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

Typical Significant Wave Height

2.7ft
Mean: 3.2 ft
P10–P90: 1.3 — 5.6 ft
Recorded extremes

0.7 — 11.6 ft

Mean Observed Wave Period

9.9secs
P10–P90: 5 — 14.8secs
Recorded extremes

3 — 25secs

Available for 718 of 720 hourly samples

Observed Wave Direction

SW

Circular concentration: 93%

Mean Water Temperature

9.1°C
P10–P90: 7.9 — 10.2°C
Recorded extremes

7.5 — 11.7°C

Compared With Previous Aprils

Historical baseline from 11,466 observations across 8 years.

Wave Height
3.2ft
0.8ft above mean
Historical mean 2.428ft
Wave Period
9.9s
1.2s above mean
Historical mean 8.7s
Water Temperature
9.1°C
0.6°C below mean
Historical mean 9.7°C

Chart showing grouped wave observations for Chesil. 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 Chesil wave buoy

Chesil is a Channel Coastal Observatory National Network wave station off Dorset's exposed Jurassic Coast. It records waves approaching Chesil Beach and the western side of Portland, providing a nearshore reference for the long shingle barrier and the communities and infrastructure behind it.

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

Metrics are rows; days run left to right.
Chesil wave buoy daily means Apr 2018Last observation shown
Metric
Mean significant wave height (ft)255744432221124575322234443312
Mean maximum wave height (ft)38710666533322368118542346665422
Mean peak period (s)88911109111011151414151214131116101010845659996
Mean zero-crossing period (s)555555776577765667775434445663
Mean energy period (s)------------------------------
Mean wave power, kilowatts per metre------------------------------
Mean peak wave directionSSWconcentration 91%SSWconcentration 96%SWconcentration 99%SWconcentration 100%SWconcentration 100%SWconcentration 95%SWconcentration 100%SWconcentration 100%SWconcentration 96%Sconcentration 93%SSWconcentration 94%Sconcentration 83%Sconcentration 86%SWconcentration 97%SWconcentration 97%SWconcentration 100%SWconcentration 99%SWconcentration 100%SWconcentration 100%SWconcentration 100%SWconcentration 97%SWconcentration 99%SWconcentration 99%SWconcentration 100%SWconcentration 100%SWconcentration 100%SSWconcentration 96%SWconcentration 100%SWconcentration 85%WSWconcentration 66%
Mean directional spread (°)38.620.720.920.619.421.822.533.853.757.456.858.460.253.342.921.818.427.118.329.552.143.124.121.319.820.339.922.951.332.5
Mean water temperature(°C)7.67.77.87.98.18.28.38.48.38.48.78.68.78.88.89.19.29.39.910.09.59.69.79.910.110.310.310.110.19.9

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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 Regional Coastal Monitoring Programme.

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

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