The St Patrick's Day parade will return to Irish streets this year after a two-year hiatus, which international guest of honour for the Dublin parade, actor John C Reilly, said is a "great opportunity to spread joy".
Up to 400,000 people are expected to attend the parade in Dublin on Thursday, which organisers have said will be the “biggest and brightest” to date.
The parade is to begin at noon at Parnell Square, travelling down O'Connell Street, moving around College Green and Dame Street, before looping down Lord Edward Street and finishing on Kevin Street at around 2pm.
Olympic and paralympic sporting heroes Kellie Harrington and Ellen Keane will be the grand marshals of the parade, while Mr Reilly, the Irish-American actor who starred in Step Brothers, will be the international guest of honour.
Speaking at an event in the Guinness Storehouse, Dublin, on Wednesday he said he "feels normal" when in Ireland.
“This is a big honour for me, actually. It might seem like a goof to just appear at a parade but to me, it has deep meaning as an Irish-American,” he said.
“It feels especially important to come here now to let people know that Ireland is open for business again. We’ve all been through so much. Obviously it’s a very difficult time in the world in many different ways and for many different people, but we can’t let that stop us from expressing our joy.”
He added: “Good things happen in Ireland one after the other if you stay open to it. It’s a special place for that reason. When you come here, people are just so welcoming. It’s good craic, as they say.”
The actor will spend several weeks in the country, and intends to explore some of the west coast before returning to his home in Chicago.
The St Patrick's Day festival events will run until Sunday in the capital, and will include performances by artists and comedians such as Lyra, Damien Dempsey, Neil Delamare and Kevin McGahern.
There will be a “festival quarter” set up in Collins Barracks, where music and talks will take place.
Gardaí said an extensive policing plan is in place, with 650 members of the force working across the city, which is on par with pre-pandemic times.
Dublin city centre off-licences have been asked not to sell alcohol until 4pm, to prevent crowds drinking on the streets. Restaurants and pubs have also been asked to ensure any alcohol sold was consumed on the premises.
Outside of Dublin, parades will also resume in most cities, towns and villages for the first time since 2019.
In Cork city, the festivities will kick off at 1pm on Thursday from South Mall, and will be live-streamed online from 12.45pm.
The theme of this year’s parade is the “ordinary heroes that have brought us through extraordinary times”.
Bray, Co Wicklow is hosting its own festival until Sunday, which will include funfairs, treasure hunts, live music and face painting.
Olympians Fiona Murtagh and Aifric Keogh are the grand marshalls for Galway's St Patrick's Day parade, which starts at 11.30am and will last for around an hour.
In Limerick, the parade will begin at noon on Thursday, while on Sunday, the Limerick International Band Championship will take place.
Waterford’s festival is a three-day event, beginning with a parade at 1pm on Thursday.
In Tullamore, Co Offaly, the parade is set to kick off at 11.30 am, with local business and sportsman Phil O’Reilly Senior being the grand marshall.
Belfast’s carnival themed parade begins at the City Hall at 1pm, lasting until 2.30pm.
The weather is forecast to be mostly cloudy, with showery rain, according to Met Éireann.
Through the afternoon, drier and brighter weather will follow from the west with showers becoming isolated and sunny spells developing. Highest temperatures will be between nine and 13 degrees.