The heatwave looks set to peak today with Met Éireann forecasting a drop in temperature and cloudy weather for the weekend.
A spokeswoman told
ireland.com
temperatures will remain in the low 20s but there will be a good deal of cloud with showery rain in parts.
She said it would be dry and sunny early next week without quite reaching the highs of yesterday and today.
A high of 29°C was recorded in Kilkenny yesterday and temperatures over 28°C have been recorded already today in Mayo and Offaly.
However much of the east and south coast was today cooler where mist and fog lingered.
A number of flights leaving Dublin airport were delayed and many were cancelled due to heavy fog.
An Aer Rianta spokeswoman said passengers should expect delays of up to two hours. Twenty-five inbound and outbound flights have been cancelled and a number have been diverted away from Dublin.
She said passengers should consult their airline for information on delays and check-in times.
Tens of thousands of passengers will be affected by the delays with some 65,000 to 70,000 passing through Dublin on an average weekend at this time of the year.
This weekend sees the opening of the 30th Kilkenny Arts Festival. The 10 day-programme will feature theatre, music and visual arts exhibitions from across Europe and beyond.
The organisers have promised this year's festival will build on the achievements of the last three decades, and 2003 sees an international line-up with artists from over a dozen countries exhibiting.
The 130th Dublin Horse Show will continue until Sunday with a number of events, including, International Grand Prix sponsored by Samsung, taking place over the two days.
The Tullamore Show and the AIB National Livestock Show takes place on the grounds of Charleville Castle. The event is expected to attract upwards of 40,000 visitors.
On the sporting front the weekend is dominated by the All Ireland hurling clash between Cork and Wexford. The match takes place in Croke Park on Sunday and throw in is at 3.30 p.m.
Castlebar will host the All Ireland football quarter final replay between Galway and Donegal and throw is at 3.30 p.m. on Sunday also.