Mayo found itself at the centre of the Irish weather record books on 10 November 1999, when Knock Airport recorded the highest mean sea level pressure ever measured in Ireland during the month of November.

The barometer reached 1046.0 hectopascals (hPa) as a powerful area of high pressure brought settled, dry and exceptionally calm conditions across the country.

The lack of wind was particularly remarkable. Knock Airport recorded a maximum gust of just 3.5km/h, while the mean wind speed was a near-still 0.2km/h.

Despite the settled conditions, temperatures remained close to seasonal averages, with daytime highs generally ranging between 9 and 12 degrees nationwide.

The record was part of an extraordinary year for Irish weather extremes.

In March 1999, Beenreagh Mountain in Co Kerry recorded 650mm of rainfall, the highest monthly rainfall total ever measured in Ireland. On 20 April, Cloone Lake, also in Kerry, recorded 105.6mm of rain in a single hour, setting a national hourly rainfall record.

While Knock’s November pressure record remains in place, Ireland’s all-time highest mean sea level pressure was subsequently recorded at Malin Head in Co Donegal.

On 20 March 2020, the station registered 1051.2hPa, surpassing the previous national benchmark and setting a new record for atmospheric pressure in Ireland.