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Chesil wave buoy daily means for Jan 2021

Daily means from the Chesil wave buoy for Jan 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

1,485 wave-buoy observations covered all 31 days. Typical wave height was 3.4 ft (10th–90th percentile 0.7–7.7 ft), while mean average of more than one wave period type was 8.6 seconds (10th–90th percentile 4.8–12.9 seconds). Mean water temperature was 8.7°C (10th–90th percentile 8.3–9.5°C). 22 of 5,848 checked values (0.4%) were excluded by quality control. Across 11 comparable years, mean wave height was below the same-month mean of 4.3 ft and mean wave period was below the same-month mean of 9.1 seconds.

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

Typical Significant Wave Height

3.4ft
Mean: 3.7 ft
P10–P90: 0.7 — 7.7 ft
Recorded extremes

0.4 — 13.3 ft

Available for 742 of 744 hourly samples

Mean Observed Wave Period

8.6secs
P10–P90: 4.8 — 12.9secs
Recorded extremes

1.9 — 22.2secs

Available for 741 of 744 hourly samples

Observed Wave Direction

SSW

Circular concentration: 89%

Mean Water Temperature

8.7°C
P10–P90: 8.3 — 9.5°C
Recorded extremes

8.2 — 9.9°C

Available for 742 of 744 hourly samples

Compared With Previous Januarys

Historical baseline from 16,333 observations across 11 years.

Wave Height
3.7ft
0.6ft below mean
Historical mean 4.298ft
Wave Period
8.6s
0.5s below mean
Historical mean 9.1s
Water Temperature
8.7°C
0.4°C below mean
Historical mean 9.1°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 Jan 2021Last observation shown
Metric
Mean significant wave height (ft)11111111114545353481075453535766
Mean maximum wave height (ft)21122211116867484613161186758581199
Mean peak period (s)8766761013545777117108881012119127111091316
Mean zero-crossing period (s)5356554453455565445666655555579
Mean energy period (s)-------------------------------
Mean wave power, kilowatts per metre-------------------------------
Mean peak wave directionSWconcentration 99%SWconcentration 90%Sconcentration 94%SSEconcentration 99%SSEconcentration 99%SSEconcentration 93%SSWconcentration 80%SSWconcentration 69%SSEconcentration 99%SWconcentration 81%SWconcentration 99%SWconcentration 100%SWconcentration 100%SWconcentration 95%SWconcentration 98%SSWconcentration 95%SWconcentration 98%SWconcentration 99%SWconcentration 100%SWconcentration 100%SWconcentration 100%SWconcentration 100%SWconcentration 100%SWconcentration 100%SSWconcentration 96%SWconcentration 99%SSWconcentration 91%SWconcentration 100%SWconcentration 100%SWconcentration 99%SWconcentration 100%
Mean directional spread (°)54.951.138.134.935.638.557.760.934.433.718.418.823.220.635.219.637.026.416.116.714.018.921.321.039.125.330.926.416.923.922.5
Mean water temperature(°C)9.89.79.69.59.39.18.98.98.88.78.58.48.68.58.58.58.58.58.58.68.68.58.68.78.48.38.38.48.58.68.7

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.

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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