A status yellow rain warning has been issued for 15 counties leading to further fears of flooding in the midlands and west.
Met Éireann says up to 25 millimetres of rain could fall between Sunday night at 8pm and 8am Monday morning.
The counties affected are Cavan, Monaghan, Donegal, Longford, Louth, Offaly, Westmeath, Meath, Clare, Tipperary and all of Connacht.
The rain is likely to be preceded by a period of snow in parts of Connacht, Ulster and north Leinster, before turning to rain later in the night.
As the ground is saturated at the moment and river levels are elevated the combined effect of rainfall and snowmelt may lead to some localised surface and river flooding.
Many areas along the River Shannon are on alert, with much farmland around Carrick-on-Shannon and Athlone already underwater.
Meanwhile, a status yellow warning for wind has also been issued for Donegal and is in place until 8pm tonight. Gusts of up to 110 km/h or higher are expected in exposed coastal areas.
