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Chesil wave buoy daily means for Jul 2021

Daily means from the Chesil wave buoy for Jul 2021, 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 1.5 ft (10th–90th percentile 0.5–4.3 ft), while mean average of more than one wave period type was 7.4 seconds (10th–90th percentile 4.3–10.6 seconds). Mean water temperature was 16.5°C (10th–90th percentile 15.4–17.6°C). 15 of 5,846 checked values (0.3%) were excluded by quality control. Across 11 comparable years, mean wave height was below the same-month mean of 2.2 ft and mean wave period was above the same-month mean of 6.7 seconds.

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

Typical Significant Wave Height

1.5ft
Mean: 2 ft
P10–P90: 0.5 — 4.3 ft
Recorded extremes

0.4 — 13 ft

Mean Observed Wave Period

7.4secs
P10–P90: 4.3 — 10.6secs
Recorded extremes

1.7 — 20secs

Available for 741 of 744 hourly samples

Observed Wave Direction

SW

Circular concentration: 91%

Mean Water Temperature

16.5°C
P10–P90: 15.4 — 17.6°C
Recorded extremes

14.4 — 22.9°C

Compared With Previous Julys

Historical baseline from 16,334 observations across 11 years.

Wave Height
2ft
0.2ft below mean
Historical mean 2.231ft
Wave Period
7.4s
0.7s above mean
Historical mean 6.7s
Water Temperature
16.5°C
In line with the historical mean
Historical mean 16.5°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 Jul 2021Last observation shown
Metric
Mean significant wave height (ft)1124374222222211110001121224473
Mean maximum wave height (ft)212641064332233211111112222375105
Mean peak period (s)666879785678966791011101312878656576
Mean zero-crossing period (s)3434454444444444555553455434454
Mean energy period (s)-------------------------------
Mean wave power, kilowatts per metre-------------------------------
Mean peak wave directionSWconcentration 99%SWconcentration 99%SSWconcentration 90%SWconcentration 99%SWconcentration 97%SWconcentration 98%SWconcentration 100%SWconcentration 99%SWconcentration 99%SWconcentration 99%SWconcentration 100%SWconcentration 86%SWconcentration 98%SWconcentration 99%SWconcentration 99%SWconcentration 99%SWconcentration 90%SWconcentration 84%SWconcentration 67%SSWconcentration 80%Sconcentration 77%Sconcentration 74%SWconcentration 74%Sconcentration 89%SWconcentration 98%SWconcentration 99%SWconcentration 99%SWconcentration 100%SWconcentration 99%SWconcentration 98%SWconcentration 100%
Mean directional spread (°)45.053.741.628.229.315.821.437.835.736.845.752.048.243.347.755.160.964.967.064.270.261.452.142.756.141.633.021.326.219.424.6
Mean water temperature(°C)15.015.215.315.515.715.515.816.216.016.015.915.916.116.016.116.316.917.518.118.118.518.417.116.916.816.916.817.017.217.217.3

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.

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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