A heatwave is possible this week, although cooler temperatures tomorrow may prevent Ireland from reaching that threshold, Met Éireann has said.
A heatwave is declared when there are five days or longer of temperatures of 25C or more in the same location.
Temperatures could rise as high as 27C in parts of the country today, while Oak Park Weather Station in Co Carlow recorded a high of 28.1C yesterday.
"Today will be warmest in parts of Ulster and north Leinster, while the rest of the country will experience temperatures around the mid 20s," Met Éireann forecaster Aoife Kealy said.
"It will be little less warm in Munster due to cloud," she added.
Ms Kealy said that while a heatwave is possible, cooler temperatures tomorrow may prevent Ireland reaching the point where a heatwave could be declared, with the south and southeast expected to enjoy the best of the heat tomorrow with highs of up to 25C.
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Warm conditions will continue on Friday and into the weekend, with the mercury hovering around the mid-20s mark.
Amid the high temperatures, a Status Yellow thunderstorm warning will be effect for Clare, Kerry and Limerick between 3pm and 9pm tonight.
Ms Kealy said showers in these three counties will turn heavier as the day goes on, with thunder possible in some parts.
There is a risk of localised flooding, lightning damage and difficult travelling conditions.
Currently, it is not likely that any further thunderstorm warnings to be issued, she said.
As for the possibility of a high temperature warning being issued, Ms Kealy said current forecasts deem it unlikely that one will be issued by Met Éireann.
For a high temperature warning to be issued, temperatures must surpass 27C and cover a widespread area.
