Biggest wave ever hits Donegal

The record 20.4 metre wave was by a M4 weather buoy at 2pm on Tuesday, December 13, 2011 and was “a maximum individual wave height.”

The M4 (and the M2 in the Irish Sea) are from a new generation of weather buoys with the ability to measure maximum wave height; this new M4 has been on station here since June 2011.

Also, at 1pm on the same day a “Significant Wave Height” of 14.7m was recorded at the M4 which was another record wave height at that location.

The Significant Wave Height is defined as the average height of the highest one-third of the waves and that is what our forecasts of wave height refer to.

In general, the highest wave of all will be about twice the Significant Wave Height.