Last month was the warmest September in more than a century in some parts of Ireland, according to Met Éireann.
"Temperatures were above normal throughout the month," the weather service's monthly bulletin said.
Dublin's Phoenix Park had its warmest September since 1865, according to the bulletin, and it was Malin Head's hottest since 1895.
Last month's temperatures were up to three degrees higher than September's mean values of 15 to 16 degrees, the report said. "These values are even higher than those for a typical August."
"Several stations had their sunniest September day for more than 20 years."
The bulletin characterised the mild weather as a side effect of deep Atlantic depressions, which made September in Ireland especially windy and wet.
"Rainfall totals for the month were above normal everywhere," the bulletin stated. "It was a particularly wet month in parts of the west and south."
Belmullet, for example, had its wettest September since 1985, according to the report.
"Shannon airport's fall of 48mm on the 21st was its highest daily fall for September since the station opened in 1945."