Update 1.04pm: Met Éireann has issued a status yellow weather warning for the entire country.
The forecaster says "high-intensity" rainfall can be expected on Saturday night due to the remnants of tropical Storm Ernesto.
The warning comes into place on Saturday, August 18 at 8pm and will remain in place until 8am on Sunday, August 19.
Met Éireann says rainfall totals of up to 20mm could occur quite widely with higher falls locally. The forecaster will continue to monitor the situation.
Earlier: Heavy rain due Saturday as Ireland to feel the effects of Storm Ernesto
Saturday is set to see some heavy rain, so if you are heading out, pack the umbrella and the rain jacket.
Friday will see patches of rain and tomorrow will begin dry but will quickly take a turn for the worse.
Met Éireann says heavy rain will develop in the afternoon "along the Atlantic Seaboard and will become widespread early Saturday night."
According to weather service AccuWeather, winds from subtropical Storm Ernesto - which is currently over the Atlantic Ocean - will generate "significant swells over part of the north-central Atlantic".
These swells will reach Ireland and UK on Saturday, bringing the heavy rain with it.
Alan O'Reilly from Carlow Weather said the subtropical storm will bring strong winds but nothing too extreme.
"It's not going to be anything significant in terms of wind speed. The south-west might see gusts of more maybe 70-80km/h," said Mr O'Reilly.
Despite some bad rain, Saturday will be very warm and humid.
Temperatures will be high with Munster and Leinster seeing highs of 25 degrees, while the north and west will see temperatures between 18 to 20 degrees.
Met Éireann predicts that Sunday will begin with rain but as the day progresses it will become brighter and drier in most places.
Sunday will again be humid with temperatures in the high teens to low 20s.
- Digital Desk