A status yellow thunderstorm warning has come into effect for 18 counties.
Met Eireann says there'll be thundery downpours and a risk of spot flooding across Leinster, Cavan, Donegal, Monaghan, Leitrim, Roscommon and Sligo.
The warning's valid until 8pm.
Rain in the east & northeast today with sunshine & showers elsewhere🌧️⛈️
There'll be heavier showers with a chance of thunderstorms & localised flooding from around lunchtime until early evening;areas at risk the counties north & east of a line from Sligo to Wexford
Max 17 to 20C pic.twitter.com/wOsZVbxN7g
— Met Éireann (@MetEireann) August 21, 2021
Joanna Donnelly from Met Éireann says anyone travelling today needs to take care if they find themselves driving in a thunderstorm.
She said: "If you do encounter one of these heavy showers, you're going to encounter significantly reduced visibility.
"You'll really need to slow your speed right down - maybe even turn on your foglights."
Showers are expected to die out this evening, leading to a dry but rather cloudy Sunday in most areas.