A number of severe weather warnings are in place as Storm Desmond moves across the country.
A status red rainfall warning is in place for large parts of the west and northwest with flooding likely in many areas.
The warning is due to remain active until the early hours of Sunday morning.
Wind and rain warnings are also in place for other parts of the country.
Emergency services, local authorities and civil defence crews are working to prevent flood damage in many areas of the country.
The army was called to evacuate an elderly couple from their home near Glenflesk in Co Kerry due to flooding. However, they managed to get out safely before the army arrived.
The Glenflesk area has been badly affected by rising water levels and the main Cork to Killarney road is impassable there.
Emergency services are also reporting that a number of vehicles have been abandoned on flooded roads.
Motorists who are forced to leave their vehicles are asked to contact gardaí to give the vehicle's location.
The army has platoons on standby at barracks at Cork, Limerick, Galway and Donegal.
Trucks with high wheel bases are being deployed to assist ambulance crews at Bantry in Co Cork and Kenmare and Tralee in Co Kerry.
The trucks will be used to respond to calls from areas that are inaccessible to ambulances due to flooding.
Houses at a number of estates in Tralee have begun to flood, however flooding has receded in Kenmare, with only a handful of properties damaged.
Kerry County Council, fire service and Civil Defence personnel are working with local residents in the area.
Motorists are being urged to drive with care, with flooding and downed trees reported in some areas.
Gardaí in Galway say there is bad flooding around Kilmore near Ballinasloe and on the Moycullen Road on the N59.
There is also localised flooding on the coast road from Galway city to An Spideal, where there are very high waves.
Motorists are advised to avoid the N17 Tuam road at Claregalway as one lane is closed due to flooding.
Gallery: Storm Desmond
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Drivers are advised to avoid coastal roads, particularly around the Salthill promenade.
Heavy rain was reported across Roscommon overnight, with large amounts of surface area water on the roads as a result.
Flooding has also been reported around Glenisland in Castlebar, Co Mayo.
In Crossmolina, Co Mayo there is very bad flooding affecting the town centre after the River Deel burst its banks.
Shops and homes have been flooding and council workers are at the scene. The N59 Belmullet-Ballina road is completely impassable through the town.
Cork County Council has issued a red alert warning for flooding in Bandon, as water levels continue to rise there.
The council says there is a risk of severe flooding in the town.
The Bandon river is beginning to flood the streets of the town centre.
Water levels up-stream in Dunmanway have begun to recede, which should mean damage to properties in Bandon may be minimal, but the situation for the next hour or so will be on a knife edge.
County Council staff, Civil Defence and the army are currently sand bagging there
Elsewhere in Cork, rising water levels on the River Lee, close to its source at Ballingeary are causing concern for flooding in the village. Several roads in the area are impassable due to flooding.
Many local roads in the Crookstown, Inchigeelagh and Dunmanway areas are impassable.
The army and Civil Defence have been mobilised and council crews have been distributing sand bags to property owners.
The Moll's Gap road between Killarney and Kenmare is currently closed due to flooding, and there's flooding on the alternative route via Kilgarvan too, although that road remains passable.
Management at Killarney National Park advised the public not to visit the park due to weather conditions.
Kerry County Council amenity sites at Cahirsiveen, Dingle, Kenmare, Killarney and Milltown will remain closed, but will re-open on Monday.
Kerry County Council advises that the main Macroom to Killarney road at Glenflesk is closed because of flooding.
Local diversions are in place.
Kerry fire crew pumping flood water from Muckross Rd Killarney in winds & driving rain. Long day for many KCC staff! pic.twitter.com/4uh32BlHbd— Kerry County Council (@countykerry) December 5, 2015
The R569 Kilgarvan Road at Loo Bridge, the N22 at Glenflesk and the Barradubh-Glenflesk road are also closed.
A large number of roads are closed in Co Clare, including the N85 north of Inagh.
Clare County Council has established an Emergency Call Centre for members of the public to report any fallen debris and flooded roads.
The emergency number - 1890 252943 - will be operational from 5.30pm this evening.
Motorists in Co Sligo will also face a similar situation, with flooding affecting the N4 Ballysadare road, the Scarden-Strandhill road and some roads in the Ransboro area.
A number of routes in Donegal are also impassable, including the R261 Ardara-Killybegs road outside Ardara.
The N56 Letterkenny-Dunfanaghy road between Kilmacrenan and Creslough, the Castlefinn bridge and the Portnoo-Naran road in the Glenties are all also impassable.
In Leitrim, the Manorhamilton-Dromahair road is closed at Kilcosey due to flooding, while the R281 Kinlough-Rossinver road is closed due to a landslide.
A number of local roads across the midlands are also closed, with local authority staff working to clear the debris.
Farmers in the region say up to 10,000 acres are under water in the Shannon basin and they expect flooding across the basin until rainfall decreases.
Storm grounds many flights from Dublin, Cork
Flights to and from Irish airports have been affected by the weather, with some cancelled and others diverted.
Ryanair has cancelled a series of flights from Dublin Airport, while they are also not operating at Cork Airport.
A full list of cancelled flights is available on their website.
Cork Airport is advising intending passengers to contact their airline for updates.
Aer Lingus has cancelled 39 regional flights, affecting 2,000 passengers in Ireland and at a number of UK airports.
The propeller driven aircraft used by Aer Lingus Regional are easily affected by bad weather.
Some passengers to Edinburgh, Glasgow and Manchester were accommodated on larger aircraft and all passengers are entitled to re-book later flights or get a refund.
Six Aer Lingus planes had to make more than one attempt at landing in Dublin airport due to cross winds.
Two of the six diverted to Shannon and passengers are being taken by coach to Dublin.
Shannon Airport continues to operate as normal, and has handled six diversions from Dublin and three from Cork.
Airlines are organising transport for passengers.
Irish Ferries has said that due to the conditions all Jonathan Swift fastcraft sailings have been cancelled today.
It says passengers can be accommodated on cruise ferry sailings.
Further information is available on the Irish Ferries website.
Power restored to 12,000 homes by ESB crews
Gale-force winds have caused some disruption to electricity supply, mainly in the west and northwest.
ESB Networks has restored power to 12,000 homes and crew are continuing to work on getting power back to another 850 homes.
The company says it is likely that 600 homes in Crosmolina, Co Mayo and Killarney, Co Kerry will be without power overnight.
ESB Networks has warned that as the winds are set to continue, further outages are likely.
It says ESB crews will remain on alert to deal with damage to the electricity network and restore power.
If you see an damaged Network or Fallen wires DO NOT TOUCH DO NOT GO NEAR RING 1850372999 OR 112 IF NO CREDIT #Staysafe— ESB Networks (@ESBNetworks) December 5, 2015
Several sporting events have been cancelled or postponed, including GAA inter-provincial championship semi-finals and Leinster's rugby match against Glasgow Warriors.
The Killarney Historic Stages Rally, which was due to take place today, has also been called off due to the weather.
More than 150 cars, featuring a number of former Irish and British champions, were due to take part.
Gardaí in Clonakilty advise that the weather has forced the cancellation of the annual marathon.
*Turf Club News* Navan cancelled today due to a deterioration in weather conditions.— Horse Racing Ireland (@GoRacing) December 5, 2015