A nationwide orange thunderstorm warning was active until 9am, while a separate orange alert for all of Munster, Wexford, Carlow, Wicklow and Kilkenny has been updated to include Laois, Offaly, Kildare and Dublin also.
This alert was due to expire at 4pm on Monday however, it will now remain in effect until 10pm.
The national forecaster warned: “Thunderstorm activity expected. Due to the sporadic nature of development, not all areas will be affected. Heavy downpours of rain and hail will occur in places. Flooding where heavy downpours occur.”
Meanwhile, the UK Met Office has issued a Status Yellow thunderstorm warning for counties Antrim, Armagh, Down, Fermanagh, Tyrone, Derry in place until midnight tonight.
Met Éireann meteorologist Linda Hughes said there was “very widespread thunderstorms overnight right across the country”.
"All provinces seeing thunderstorms and quite slow moving, intense lightning and heavy rainfall as well. So, really most places seeing thunderstorm activity overnight and into this morning as well,” she said.
"While the thunderstorms have cleared now for most places, there was a few in south Leinster over the past couple of hours. More developing as we go through this morning and this afternoon, so mainly focused over the south and southeast but really right up across Leinster there are more thunderstorms forecast to develop through later this morning and the afternoon as well and potentially into this evening too.”
Speaking on RTÉ’s Morning Ireland,Ms Hughes warned of further heavy rainfall, spot flooding and the chance of hail, which she said motorists should be particularly conscious of.
"The ground is so dry, so any rain that does fall on it isn’t going to be absorbed, it’s going to run off the surface… So certainly through the rest of today, there is a likelihood of spot flooding from heavy and slow moving downpours,” she said.
“As well, there is a risk of hail in these thunderstorms. They are quite intense thunderstorms, so there is a risk of hail and that is very hazardous for drivers… So drivers should really take care when these orange warnings are out.”
Ms Hughes added that the thunderstorms have marked the end of recent heatwave conditions. She said “typical August temperatures” will return from tomorrow onwards.
Highest temperatures today will range from 15 to 17 degrees in the north and west, and between 18 and 23 degrees.
Tonight showers will gradually die out in the south to leave a mostly dry night with clear spells and lowest temperatures of 10 to 14 degrees, warmest near the east coast.
Met Éireann said tomorrow will be cooler and quite cloudy with scattered light showers, although many areas will have a dry day. Highest temperatures of 15 to 19 degrees are forecast, mildest in the south.
Showers will die out early on Tuesday night, leaving a dry night with a mix of cloud, clear spells and lowest temperatures of eight to 12 degrees.
Met Éireann said Wednesday will be a largely dry day with a mix of cloud and sunny spells in the morning and more widespread hazy sunshine developing in the afternoon. Highest temperatures of 16 to 19 degrees are expected, warmest along the south coast.
There will be clear spells early on Wednesday night for eastern parts, however, rain will move in from the west overnight. Lowest temperatures will range from nine to 13 degrees, mildest in the west.
On Thursday a band of rain, which may turn heavy at times, will cross the country through the day. Met Éireann said it will be followed by scattered showers through the evening, clearing to more widespread sunny spells in the west. Highest temperatures of 16 to 19 degrees are forecast.
Clear spells and scattered showers are expected on Thursday night. It will be mild with temperatures generally not falling below 10 to 13 degrees.
On Friday scattered showers will gradually ease through the day, while a band of rain will approach western coasts later in the day. Highest temperatures of 15 to 18 degrees are forecast.
"Current indications suggest that the weekend will be changeable with occasional rain or showers,” Met Éireann said.