Met Éireann has issued a Status Yellow rain warning across Ireland.
The warning will be valid from 6 pm today until 1 am tomorrow.
It initially only concerned six counties in the South East, but it has now been expanded.
From 7 pm tonight until 3 am tomorrow, heavy rain and a few thunderstorms are expected to move north, according to forecasters.
Met Éireann’s added some lightning and spot flooding is also possible.
A Status Yellow thunderstorm warning will also be in place for Antrim, Armagh, Down, Tyrone, and Derry from 8 pm today until 4 am tomorrow.
According to Met Éireann, It is expected to be mostly dry on Monday morning with sunshine.
However, clouds will build during the day and showery rain will spread gradually northwards over the country.
The highest temperatures will range from 16 to 20 degrees Celsius.
Tonight, persistent rain will continue to spread northwards. The lowest temperatures will range from nine to 12 degrees.