Some 150,000 people are expected to attend over the course of the national and world ploughing championship in Tullow, Co Carlow, which opens today.
Local business people estimate that the event, which costs almost €2 million to stage, will inject more than €30 million into the local economy.
President Mary McAleese will officially open the World Ploughing Championships tomorrow afternoon.
Taoiseach Bertie Ahern and Tánaiste, Michael McDowell are expected on the site on Friday.
Minister for Agriculture and Food Mary Coughlan who officially opened the national ploughing event at noon, will use the occasion to announce a new policy on milk quotas later today.
Met Éireann has warned of very windy conditions today with gusts of up to 120km/h. Winds and rain are expected to ease later by evening with highest temperatures 17 to 20 degrees.
Tomorrow will be a bright, fresh day with sunny spells and a few scattered showers.
AA roadwatch report traffic as busy but moving on all approaches to Tullow (N80, N81, N9, N11 & R725) and a major Garda traffic plan is in operation.