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Chesil wave buoy monthly means for 2021

Monthly means from the Chesil wave buoy for 2021, including available wave height, period, direction, wind and sea temperature data.

Last observation shown

Data available:  to 

Latest

Period Summary

Programmatically generated summary. Hog Says

17,503 wave-buoy observations covered all 365 days. Typical wave height was 2 ft (10th–90th percentile 0.8–6.3 ft), while mean average of more than one wave period type was 8.4 seconds (10th–90th percentile 4.3–12.9 seconds). Mean water temperature was 12.6°C (10th–90th percentile 8.3–17.6°C). 208 of 69,069 checked values (0.3%) were excluded by quality control.

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

Typical Significant Wave Height

2ft
Mean: 2.9 ft
P10–P90: 0.8 — 6.3 ft
Recorded extremes

0.4 — 15.1 ft

Available for 8,750 of 8,759 hourly samples

Mean Observed Wave Period

8.4secs
P10–P90: 4.3 — 12.9secs
Recorded extremes

1.7 — 25secs

Available for 8,727 of 8,759 hourly samples

Observed Wave Direction

SW

Circular concentration: 90%

Mean Water Temperature

12.6°C
P10–P90: 8.3 — 17.6°C
Recorded extremes

7.1 — 22.9°C

Available for 8,749 of 8,759 hourly samples

Chart showing grouped wave observations for Chesil. Use the table on this page for a text version of the same measurements. To open daily observations, use a linked month 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; months run left to right.
Chesil wave buoy monthly means 2021Last observation shown
Metric
Mean significant wave height (ft)45314122242QC rejected
Mean maximum wave height (ft)675262333647
Mean peak period (s)91210888868889
Mean zero-crossing period (s)565454444545
Mean energy period (s)------------
Mean wave power, kilowatts per metre------------
Mean peak wave directionSSWconcentration 89%SSWconcentration 94%SWconcentration 94%SSWconcentration 79%SWconcentration 96%SSWconcentration 88%SWconcentration 91%SSWconcentration 91%SSWconcentration 89%SWconcentration 96%SWconcentration 83%SWconcentration 92%
Mean directional spread (°)29.728.436.843.631.148.043.033.339.929.034.727.8
Mean water temperature(°C)8.78.18.59.711.313.916.517.417.815.813.210.2

Swipe sideways to see more months.

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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