There is a flood risk in 17 counties as heavy rain is due to fall on already saturated ground.
On Tuesday morning, Met Eireann issued a yellow warning for rain applying to all of Leinster as well as Tipperary, Cavan, Monaghan, Cork, and Waterford.
The warning will be in effect between 11pm on Tuesday and 11pm on Wednesday.
It is a significant expansion of the advisory which was first announced on Monday.
The forecasting agency said there is a risk of flooding, poor visibility and difficult travelling conditions in these areas, which are also experiencing high river levels.
The inclement conditions will be exacerbated by strong and gusty south-easterly winds in five of these counties.
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Wexford, Wicklow, Meath, Louth and Dublin will also be under a yellow warning for wind, with Met Eireann also cautioning against wave overtopping amid high tides.
The wind warning is between 11pm on Tuesday and 1pm on Wednesday.
The double warning applies to areas in the east of the country which have been severely affected by flooding in recent weeks.
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