A Status Red wind warning has been issued for Cork and Kerry, from 6am on Tuesday while Clare will be under the same warning from 4pm.
Status Orange alerts have been extended to Mayo, Galway, Limerick, Waterford, Wexford, Wicklow, Dublin, Meath and Louth.
A Status Red violent storm marine warning is in place for the west coast from Roche’s Point to Valentia to Erris Head, with Force 11 gusts possible, and an Orange warning covering all other sea areas.
Motorists have been urged to only undertake vital journeys - while people in Cork and Kerry, were urged to stay indoors and away from exposed coastal areas.
Status Yellow alerts are in place for all other Irish counties amid fears Storm Barra will deliver a major storm surge which, at high tide, could result in coastal flooding from Galway to Cork.
Speaking this afternoon, Taoiseach Micheal Martin issued a stern warning ahead of Storm Barra as he said the Government is “very, very” concerned.
Mr Martin said that travel should be kept to a minimum in counties which have orange or red weather warnings and said that tomorrow is set to be a “difficult day”.
“Tomorrow will be a very, very difficult day from a storm perspective,” he said.
The Taoiseach said an emergency meeting of the national emergency co-ordination group took place in Government buildings this afternoon about the upcoming storm, attended by Housing Minister Darragh O’Brien.
He added: “It’s very, very serious. We would urge people to stay at home, unless it’s necessary, in terms of travel in the counties concerned, to watch out for your weather alerts.
“I think it’s very important that we get the message out there to the public at large that we are dealing with a very, very serious storm in Storm Barra tomorrow and right into Wednesday.”
He said that people “must avoid the coast at all costs” in counties which are set to be hit harder and warned that there will be localised flooding and fallen trees.
He said that counties with orange or red alerts “travel should be kept to minimum”.
The threat posed by the second Atlantic storm of the season is exacerbated by the fact its impact over Ireland will last for almost a full 24 hours - increasing the potential for structural damage, fallen trees and flooding.
The storm is so vast that its eye could extend over several Irish counties.
Greatest concern is focused on the danger posed by raging seas and damaging winds in coastal areas of the west and south west.
Ireland's fishing fleet has already started to flee to port ahead of the arrival of Storm Barra.
While four flights from Cork
Airport which were due to depart tomorrow morning have been cancelled.
Aer Lingus, KLM and British Airways have all cancelled flights for London and Amsterdam.
Airlines are currently carrying out a review of the situation and will provide an update on other flight cancellations later this evening and early tomorrow morning.
The storm will make landfall on Ireland's west and south west coast from 6am - and Met Éireann warned winds and heavy rainfall could last for up to 24 hours.
The Coast Guard appealed to people to put public safety first.
"We are appealing to all mariners and coastal communities to be mindful of the severe weather warnings and to note the imminent arrival of Storm Barra," ICG operation manager Micheál O'Toole said.
"Walkers are advised to avoid any exposed areas, including seafront and cliff walkways, as they may be hit by sudden gusts, exposing themselves to unnecessary danger."
"All other forms of open water recreation should be avoided, including by experienced practitioners, as it may result in arousing public concerns and causing rescue services to be alerted."
Mr O'Toole urged people to stay back, stay high and stay dry.
"Please remain vigilant, avoid any unnecessary travel and to monitor Met Éireann weather forecasts. If you see somebody in trouble on the water or on the coast dial 112 or use marine VHF channel 16, and ask for the Coast Guard.”
Major concern is also focused on the potential storm surge - with a severe risk of coastal flooding in exposed parts of the west and south west.
The storm surge flooding concern is centred on Galway, Limerick and Cork.
Cork City Council warned city centre residents and traders of the risk posed by flooding if the storm surge coincides with high tide at 7am.
The most vulnerable areas are the city centre quays - and people were urged not to leave their cars parked overnight in vulnerable quay areas.
Meanwhile, a school in Co Cork which suffered significant damage during Hurricane Ophelia after the roof of its gym blew off has announced it will remain closed tomorrow.
Douglas Community School said it will not open due to the red alert in place for the rebel county.
Restorations to the school after Ophelia in 2017 cost nearly half a million euro.
Council chiefs in Status Red and Status Orange counties have staged emergency meetings to assess the potential impact of the storm and to ensure all precautionary preparations are taken.
They have triggered their Crisis Management Teams while local coordination groups are now working to assess defence mechanisms in the most vulnerable coastal areas.
Tuesday’s high-level warnings remain in place until 6am on Wednesday, while Yellow wind and rain warnings remain in place for the whole country until 6pm on Wednesday.
Gardaí and the Road Safety Authority (RSA) urged people in the five most severely impacted counties to only undertake necessary journeys on Tuesday.
Greatest concern is focused on the potential threat posed by falling trees.
Wind gusts could reach 140kmh while sustained wind speeds of up to 80kmh are likely in many areas.
Such is the risk of property damage that householders in the most threatened counties have been urged to secure all garden furniture and stand-alone exterior Christmas decorations.
Water Safety Ireland and the Irish Coast Guard urged people to stay away from coastal areas given the danger posed by severe wind gusts and stormy seas.
People have been especially warned not to approach exposed coastal areas to take selfies or photographs of the storm.
Met Éireann's Liz Walsh said Storm Barra will not be speedily resolved with winds and stormy seas likely to last for 24 hours or longer.
"There will be storm force winds in places, high seas and coastal flooding as well as heavy, squally falls of rain," she said.
"There will also be some transient falls of sleet and snow in the north west."
Winds are forecasted to reach Violent Storm Force 11 on Irish coastal waters from Galway to Cork.
She said the damaging winds will mostly pose a serious risk of bringing down trees - with major caution by the public required as a result.
Power outages are expected across the south and south west.
ESB have emergency repair crews on standby but warned the public that they will only be deployed when it is safe to do so.
Contractors are on standby in five counties to tackle fallen trees on roads and infrastructure.
People were urged not to approach power lines brought down by fallen trees.
"If there are fallen or damaged wires, keep clear and phone ESB Networks immediately on 1800-372999," a spokesperson said.
A number of tourist attractions have announced they will be closing on Tuesday due to concerns over Storm Barra.
The Cliffs of Moher visitor experience will remain closed all day. The public is being urged not to visit the popular attraction as "winds on site will be extremely strong and extremely dangerous as a result."
Fota Wildlife Park in Cork will also close.
"We are in the process of contacting directly all bookings for this date," the park said in a statement.
"We apologise for the inconvenience caused. This decision is for the safety of our visitors as well as our animals and staff."
Johnstown Castle, Wexford is also closing. While the grounds will be off limits, the cafe will remain open as normal.
Speaking this morning, forecaster Liz Walsh told RTÉ Radio One’s Morning Ireland that the storm will be “quite longwinded”.
“Storm Barra will start to impact Ireland at around 6am tomorrow, it will actually be quite longwinded as it will last all the way through Tuesday and into Wednesday night,” .
“Worst affected looks to be those western coastal counties, Galway down to Cork in particular will be worst affected, certainly Kerry and West Cork will have potential to have even higher gusts that the orange level currently in place.
“The impacts are going to vary depending on your location, it is going to be extremely windy everywhere tomorrow not just in the western coastal counties, Dublin and Leinster will also get a fair whack of winds and certainly well into the yellow warning criteria which is gusts of 90-110km, which is not to be sniffed at, at any stretch of the imagination.
“But currently the western counties will be even higher, orange level with gusts of 110-130km and the red level you are in excess of that.”
Ms Walsh said impacts will vary depending on location, but no one should make unnecessary journeys.
“So impacts vary depending on location but they will include high winds, high seas with coastal flooding, heavy falls of rain and some transient falls of sleet and snow in the north west of the country,” she said.
“[There will be] trees down, structural damage, so secure any outdoor furniture, especially businesses that have outdoor furniture for Covid and Christmas decorations and there will be disruption to travel as well as hazardous driving conditions so we would recommend not to make unnecessary journeys tomorrow.”
“It’s coming in like a freight train on Tuesday morning,” Met Eireann forecaster Liz Walsh told Independent.ie last night.
“There will be pulses of strong winds everywhere. It’s going to be a sustained period of strong winds throughout the day,” she said.