Get to Ratheniska early if you want to beat the bad weather.
The Ploughing Championships opens today outside the Co Laois village with the weatherman warning the clouds will darken as the week goes on.
"Tuesday will be good with plenty of sunny spells," said Met Eireann's Harm Luijkx.
"But we can expect a few showers. Temperatures won't reach any higher than 14C so it might be a bit chilly but all in all it won't be too bad," he added. "Wednesday will bring more showers. But Thursday will see the worst of the weather with blustery cold conditions and plenty of rain."
National Ploughing Association managing director Anna May McHugh warned motorists to give themselves "plenty of time" to avoid any harrowing traffic hiccups.
"We are back on this site for a third year and people may say to themselves 'I know where I'm going, I'll leave a little later' but imagine if everyone said the same thing. Give yourself plenty of time to get here," she said.
The population of Co Laois will more than double as up to 280,000 people descend on the 84th instalment of the National Ploughing Championship.
Work on the special 800-acre site, which hosts the competition for a third consecutive year, started on August 4 in preparation for the mammoth event.
Last year businesses took in €39m at the festival, resulting in a €6.6m tax take for the Exchequer.
Aside from watching the world's best ploughmen battle it out to be named king of the furrow, visitors can lose themselves while wondering around the sites 1,500 stalls.
The Farming Independent and Irish Independent stand will host many must-see events (see programme below).
Music, fashion shows and cooking competitions are among the events on offer for those with a non-farming background at what is set to be the biggest event in the competition's history.
Organisers estimate more than 30,000 breakfast rolls will be consumed with more than 180,000 soft drinks sold to wash them down.
During the three-day extravaganza more than 16 tonnes of beef and three tonnes of pork will be eaten.