Two weather warnings have been issued by Met Éireann, signalling an end to the September heatwave.
The status yellow thunderstorm warnings will begin at 6am on Sunday morning for the counties of Carlow, Dublin, Kildare, Kilkenny, Laois, Wexford, Wicklow, Cork, Kerry, Limerick, Tipperary and Waterford.
There will be localised thunderstorms and slow-moving, heavy downpours giving frequent lightning and surface water-flooding. The warning will be valid until midnight on Monday.
A separate status yellow thunderstorm warning will be in place from midday on Sunday to midnight in the counties of Cavan, Monaghan, Clare, Galway, Leitrim, Roscommon, Longford, Louth, Meath, Offaly, Westmeath.
Recent days have brought only the fourth September heatwave in Ireland since records began. A heatwave is when there are five successive days with temperatures above 25 degrees. The highest temperature of the month, 28.5 degrees, was recorded at Oak Park, Co Carlow on Friday.
The thunderstorms will herald a return to cooler temperatures next week, though it will still feel pleasantly warm, with temperatures of between 13 and 17 degrees.
The weather will become more unsettled as next week progresses.