A yellow rainfall warning is in place in place for Munster and Leinster
Residents in Chapelizod, Dublin are being warned to be on alert tonight as the Liffey's water levels continue to rise.
Dublin City Council and local gardaí are urging anyone with cars in underground car parks to move them to higher ground in the area.
The ESB is also expected to increase the flow of water through the Leixlip reservoir overnight, and it is monitoring the situation after heavy rains over the past 24 hours.
The Government's emergency taskforce is warning that more homes and businesses will be flooded by the end of the day.
Following heavy rain overnight, the Shannon continues to rise and is expected to peak tomorrow, with up to 50 millimetres of rain to fall in already flood-stricken regions.
The areas most likely to be affected are in the vicinity of Parteen Weir including Springfield, Montpellier, Castleconnell, Mountshannon and the University of Limerick.
The ESB is continuing to monitor the situation.
River levels are expected to peak in the lower Shannon on Sunday and Monday.
Met Éireann says a yellow weather warning is still in place for Munster and Leinster.
Forecasters say the rain is becoming less intense, but between 20 and 25mm of rain is expected in some areas for the rest of today and tonight.
The worst affected areas are expected to be in counties Clare, Cork and Kerry, where a status orange rainfall warning had been issued earlier in the day, but has since been downgraded.
A separate snow-ice warning for Cavan, Monaghan, Donegal, Mayo and Roscommon is in place until early this afternoon.
Meanwhile farmers are joining forces with the Irish Red Cross in manning pumps to divert flood waters, which have been at high levels since Storm Desmond hit Ireland last weekend.
Hundreds of acres of farm land were under water this morning, after more than a week of heavy rainfall and worsening conditions.
Tom Turley, Chairman of the IFA Flood Project team, says his members are under particular pressure.
He says the floodwaters around Athlone are continuing to rise, but adds there is a "huge, huge community spirit" as farmers and others join together to deal with the situation.
The National Coordination Group on Recent Severe Weather says, "local authorities remain on standby and continue to monitor the situation and in the areas where further flooding may occur they are making the necessary preparations.
"These preparations are supplemented by the Defence Forces and other service providers when and where required," the group adds, also saying ESB is continuing to monitor levels in Lough Derg and making regular assessments of flows.
An emergency helpline to deal with requests for assistance from members of the public in Clare has been opened amid the continued poor weather conditions.
It is being operated by the County Council in response to the ongoing threat of flooding.
People can contact the service on 1890-252-943.
AA Roadwatch is reporting flooding issues on roads across the country, including in Wicklow, Clare, Dublin, Galway, Louth and Meath.
You can see a full list of current traffic alerts on the AA website.
Iarnród Éireann has also reported flooding on some tracks:
Trains resuming through Kilcock, operating through this section at walking speed. pic.twitter.com/eDrRqtcIQ4— Iarnród Éireann (@IrishRail) December 12, 2015
Brian Farrell from the Road Safety Authority has advised people driving on treacherous and wet roads to "slow down, you need to give yourself that extra braking distance... you also need to give yourself space when following behind trucks and buses".