The National Co-ordination Group has warned that heavy rain over the next 48 hours is likely to cause swollen rivers to flood.
The risk is heightened in slow moving rivers, such as the Shannon, the Blackwater, the Nore, the Slaney and the Barrow.
The group has advised people to heed weather warnings and says local authorities are on high alert.
Met Éireann has forecast particularly heavy rainfall in Munster.
National Co-ordination Group chairman Brian Kenny said people should keep an eye on what is happening in their local rivers and continue to monitor the weather warnings.
He said: "Any of our slow moving rivers will be more prone to flooding.
"This is because they are by nature flatter and therefore the flood waters spread more quickly."
"They also pass through major urban centres," he said.
Gerald Fleming of Met Éireann said the weather "we're experiencing isn't unusual for Ireland, although we haven't had such bad conditions in almost 15 years".
He said in the early 1990s Ireland experienced worse weather than "what we're going through" now.
Mr Fleming said a large storm system will pass over the country that is going to bring heavy rain this evening.
More heavy showers are forecast for tomorrow.
He said some rivers still rising in response to rain that fell three or four days ago.
Another weather system is moving in for Monday and Tuesday and Met Éireann has warned of bad weather lasting through next week and beyond.
Meanwhile, Helen Faughnan, from the Department of Social Protection, said officials administering aid to those hit by flooding can be reached either at emergency clinics or will be calling door-to-door.
She said: "At the minute the main requirements are toiletries, clothing, food in some cases, and emergency accommodation.
"If the local authority are not in a position to rehouse somebody, we are making the payments to house them."
Garda Inspector John Ferris has appealed to parents to be extra diligent with their young families.
He said: "We would appeal to parents in particular to exercise great care in and around waterways and piers in stormy conditions.
"Nature is beautiful but nature can be a beast. And it's very important that what can appear to be recreational and great fun doesn't end up in tragedy."
He said the gardaí have to call on the coastguard to go out and rescue these people.