National Network of Regional Coastal Monitoring Programmes

Note that these are real-time data and are not quality-controlled. Long-range graphs are plotted from a randomised subsample of half-hourly data.

St Mary's Sound

Select month:

Select File:

(i) stands for Iridium

View Chart Data

Download Spectra

Sea and Swell Summary for (10/03/2026 21:01 GMT)
Significant Wave Height (m)	1.98
Wave zero up crossing period (Spectrum Tz) (s)	5.4
Wind Wave Significant Wave Height (m)	1.94
Wind Wave Peak Period (s)	7.1
Wind Wave Peak Period Direction (°)	201
Swell Significant Wave Height (m)	0.5
Swell Peak Period (s)	11.1
Swell Peak Period Direction (°)	306.6
% Swell	6.2

Wave Spectra for date 10/03/2026 21:01:

Frequency (Hz)	Period (s)	Normalised Energy	Energy
0.025	40	0	0
0.030	33.3	0	0
0.035	28.6	0.001	0.002
0.040	25	0.002	0.007
0.045	22.2	0.004	0.012
0.050	20	0.004	0.012
0.055	18.2	0.003	0.01
0.060	16.7	0.045	0.136
0.065	15.4	0.07	0.212
0.070	14.3	0.113	0.342
0.075	13.3	0.154	0.466
0.080	12.5	0.159	0.481
0.085	11.8	0.127	0.384
0.090	11.1	0.245	0.742
0.095	10.5	0.099	0.3
0.100	10	0.434	1.313
0.110	9.1	0.492	1.488
0.120	8.3	0.519	1.572
0.130	7.7	0.896	2.711
0.140	7.1	1	3.026
0.150	6.7	0.942	2.85
0.160	6.3	0.519	1.572
0.170	5.9	0.425	1.287
0.180	5.6	0.244	0.739
0.190	5.3	0.279	0.846
0.200	5	0.209	0.633
0.210	4.8	0.242	0.731
0.220	4.5	0.195	0.59
0.230	4.3	0.169	0.51
0.240	4.2	0.104	0.314
0.250	4	0.099	0.299
0.260	3.8	0.086	0.26
0.270	3.7	0.095	0.289
0.280	3.6	0.116	0.352
0.290	3.4	0.101	0.305
0.300	3.3	0.074	0.224
0.310	3.2	0.053	0.159
0.320	3.1	0.043	0.131
0.330	3	0.033	0.098
0.340	2.9	0.031	0.095
0.350	2.9	0.024	0.074
0.360	2.8	0.029	0.089
0.370	2.7	0.032	0.097
0.380	2.6	0.022	0.066
0.390	2.6	0.021	0.063
0.400	2.5	0.009	0.028
0.410	2.4	0.016	0.05
0.420	2.4	0.016	0.047
0.430	2.3	0.011	0.034
0.440	2.3	0.008	0.024
0.450	2.2	0.012	0.036
0.460	2.2	0.008	0.025
0.470	2.1	0.01	0.03
0.480	2.1	0.012	0.038
0.490	2	0.007	0.02
0.500	2	0.011	0.032
0.510	2	0.01	0.03
0.520	1.9	0.009	0.028
0.530	1.9	0.008	0.024
0.540	1.9	0.005	0.016
0.550	1.8	0.005	0.015
0.560	1.8	0.006	0.018
0.570	1.8	0.007	0.02
0.580	1.7	0.004	0.013