St Mary's Sound wave buoy daily means for Dec 2020

Daily means from the St Mary's Sound wave buoy for Dec 2020, including available wave height, period, direction, wind and sea temperature data.

Last observation shown Thu, Dec 31, 2020, 23:00

Data available: Sun, Jul 3, 2016 to Sat, Aug 22, 2026

Monthly means for 2020

Period Summary

Hog Says

1,483 wave-buoy observations covered all 31 days. Typical wave height was 5.1 ft (10th–90th percentile 2.4–9.2 ft), while mean average of more than one wave period type was 8.8 seconds (10th–90th percentile 6.3–11.1 seconds). Typical wind was 0 mph and mean water temperature was 11.5°C (10th–90th percentile 11.1–11.9°C). 10 of 6,648 checked values (0.2%) were excluded by quality control. Across 4 comparable years, mean wave height was the same as the same-month mean of 5.4 ft and mean wave period was below the same-month mean of 9.4 seconds.

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

Typical Significant Wave Height

5.1ft

Mean: 5.4 ft

P10–P90: 2.4 — 9.2 ft

Recorded extremes

1.3 — 16.2 ft

Mean Observed Wave Period

8.8secs

P10–P90: 6.3 — 11.1secs

Recorded extremes

3.3 — 15.4secs

Available for 742 of 743 hourly samples

Observed Wave Direction

Circular concentration: 55%

Mean Water Temperature

11.5°C

P10–P90: 11.1 — 11.9°C

Recorded extremes

10.7 — 12.2°C

Compared With Previous Decembers

Historical baseline from 2,950 observations across 4 years.

Wave Height: 5.4ft; 0ft below mean; Historical mean 5.446ft
Wave Period: 8.8s; 0.6s below mean; Historical mean 9.4s
Water Temperature: 11.5°C; 0.2°C below mean; Historical mean 11.7°C

Show 10th–90th percentile ranges

About St Mary's Sound wave buoy

St Mary's Sound station lies between St Mary's and St Agnes in the Isles of Scilly. The National Network first deployed a Datawell Directional WaveRider here in May 2014, establishing a nearshore record for an archipelago exposed to Atlantic swell and important to local navigation and coastal management.

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

St Mary's Sound wave buoy daily means Dec 2020Last observation shown Dec 2020
Metric	Dec 1	Dec 2	Dec 3	Dec 4	Dec 5	Dec 6	Dec 7	Dec 8	Dec 9	Dec 10	Dec 11	Dec 12	Dec 13	Dec 14	Dec 15	Dec 16	Dec 17	Dec 18	Dec 19	Dec 20	Dec 21	Dec 22	Dec 23	Dec 24	Dec 25	Dec 26	Dec 27	Dec 28	Dec 29	Dec 30	Dec 31
Mean significant wave height (ft)	2	2	4	4	4	3	4	3	4	5	5	5	7	8	7	11	7	10	9	6	8	7	7	3	2	4	8	6	4	3	3
Mean maximum wave height (ft)	3	3	6	7	7	5	7	4	7	8	8	8	12	13	12	17	11	17	14	9	13	10	11	5	3	7	12	9	7	5	4
Mean peak period (s)	10	9	10	10	9	7	6	10	8	8	9	10	7	10	9	10	9	9	10	9	9	9	10	10	9	7	10	10	9	8	7
Mean zero-crossing period (s)	5	4	5	5	5	5	5	5	5	5	5	6	5	6	6	7	6	6	6	5	6	6	6	4	4	4	6	5	5	5	5
Mean energy period (s)	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-
Mean reported period (s)	4	4	5	5	5	5	5	4	5	5	5	6	5	6	6	7	5	6	6	6	6	6	5	4	4	4	6	5	5	5	5
Mean wave power, kilowatts per metre	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-
Mean peak wave direction	WNWconcentration 80%	WNWconcentration 55%	WSWconcentration 87%	NWconcentration 60%	Nconcentration 70%	ESEconcentration 89%	SSEconcentration 87%	Wconcentration 91%	WSWconcentration 79%	SWconcentration 93%	SWconcentration 95%	WSWconcentration 90%	SSWconcentration 97%	SWconcentration 98%	SWconcentration 96%	SSWconcentration 99%	SSWconcentration 99%	SSWconcentration 100%	SSWconcentration 98%	SWconcentration 94%	SSWconcentration 87%	SSWconcentration 100%	SSWconcentration 99%	Variableconcentration 14%	SEconcentration 60%	WSWconcentration 81%	SWconcentration 98%	WNWconcentration 66%	NNWconcentration 73%	NWconcentration 53%	NWconcentration 65%
Mean directional spread (°)	59.6	55.1	48.0	57.2	53.2	57.3	38.0	57.3	48.0	47.5	46.7	49.3	33.5	40.3	41.8	26.5	34.8	27.7	29.5	47.1	32.9	31.6	33.7	64.1	51.2	40.1	38.9	55.3	53.0	55.2	51.9
Mean reported wave direction	WNWconcentration 74%	WNWconcentration 55%	WSWconcentration 85%	WNWconcentration 40%	Nconcentration 65%	ESEconcentration 91%	SSEconcentration 86%	WNWconcentration 85%	WSWconcentration 72%	SWconcentration 91%	SWconcentration 95%	WSWconcentration 87%	SSWconcentration 97%	SWconcentration 97%	SWconcentration 95%	SSWconcentration 98%	SSWconcentration 99%	SSWconcentration 99%	SSWconcentration 99%	SWconcentration 83%	SSWconcentration 94%	SSWconcentration 100%	SSWconcentration 98%	Variableconcentration 6%	SEconcentration 64%	WSWconcentration 79%	SWconcentration 97%	WNWconcentration 58%	NNWconcentration 65%	WNWconcentration 53%	NWconcentration 60%
Mean water temperature(°C)	12.2	12.2	12.1	11.9	11.8	11.8	11.8	11.7	11.6	11.6	11.6	11.6	11.6	11.6	11.5	11.5	11.5	11.5	11.4	11.4	11.4	11.4	11.4	11.3	11.3	11.2	11.2	11.1	11.0	10.9	10.8

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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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