A status yellow rainfall warning is in place for 11 counties.
The warning is in place for Dublin, Kildare, Laois, Longford, Louth, Wicklow, Offaly, Westmeath, Meath, Cavan and Monaghan.
The warning came into effect at 7am and will be in place until 6am tomorrow.
Met Éireann said heavy rain is expected with 30 to 35mm expected.
The forecaster has said showery weather will develop over west Connacht and much of Munster this afternoon.
Temperatures will be at highs of 16 degrees and Met Éireann said some of the showers may turn heavy and thundery.
Rain is again expected tomorrow but Met Éireann says "some bright or sunny spells" will develop.
Temperatures will be at highs of 12 to 15 degrees.
Tomorrow night will see a mix of showers and clear spells with a "few patches of mist around dawn."
Thursday should be a brighter day with a mix of sun and showers expected.
Met Éireann says: "The showers are likely to be heaviest and most frequent over south Munster, south Leinster and also in the northwest of the country, with a risk of some hail and thundery downpours."
It is more of the same come Friday, with more showery weather expected.
Again there is a risk of some thundery downpours, but Met Éireann says there will be some bright or short sunny spells.
