Met Éireann has issued a status yellow thunderstorm and rain warning for most of the country.
The warning, which came into effect at 5.45pm this evening, will affect counties Cavan, Donegal, Monaghan, Leitrim, Roscommon, Sligo and Longford.
The warning is in place until 10pm tonight with localised slow-moving showers and heavy downpours expected. There is also a chance of hail.
Met Éireann has warned that localised flooding may occur and travelling conditions will be difficult.
Beyond the warning, temperatures are expected to hit a balmy 27C on Tuesday as the country prepares to bask in another week of hot, sunny weather.
However, amid the sunshine, there will be, what Met Éireann describes as, heavy showers or thunderstorms
Monday will be warm and humid with a mix of cloud and some sunny spells.
Scattered showers will develop across the country. Heavy and thundery falls are likely with potential for spot flooding in some parts.
Highest temperatures of 20C to 25C are predicted, with coastal fog at times too.
Thundery downpours are possible in Munster on Monday night, but temperatures won't fall below 14C to 16C.
Tuesday is expected to be very hot with sunny spells and light southeasterly breezes.
Top temperatures of 23C to 27C, although it will be less warm along the coasts due to sea breezes.
Localised thunderstorms may break out during the day, most likely in the west or midlands.
Tuesday night will be muggy again and temperatures aren't expected to drop below 13C.
Highs of 27C are forecast again on Wednesday and 26C is expected on Thursday with little to no wind aside from sea breezes.
Showers are expected on Friday with hazy sunny spells and highs of 25C.
Humid and warm weather with showers is likely to continue into the weekend but it may turn cloudier.
Overall, according to the national forecaster, it will be "very warm throughout the week with sunny spells along with heavy showers or thunderstorms in some parts".
The UV index and pollen count will be high.
Pollen can trigger hay fever symptoms in many people. These include sneezing and coughing, a runny or blocked nose, itchy, red or watery eyes, itchy throat, mouth, nose and ears, pain around your temples and forehead, and headache.
Meanwhile, Eirgrid has issued a system alert for the electricity system after outages were reported at a number of generators.
It said that the current low wind and solar resulted in the outages which have reduced the capacity to meet demand.
The operator of the national electricity grid said it is working to resolve the issue.
While an alert is not unusual, it is something that occurs more often in the winter.
A system alert is the lowest level of alert and has no immediate impact for users.
Check out the Irish Examiner's WEATHER CENTRE for regularly updated short and long range forecasts wherever you are.