But the 80,000 revellers refused to let the washout weather dampen their spirits, enjoying some of the most electrifying performances Oxegen has ever seen.
Given the huge crowds, there was little trouble, with 91 arrests for public order, assault, motoring and drugs offences over the three days.
The alleged glass-bottle stabbing of a 28-year-old man on Friday is also being investigated. The victim was taken to St James's Hospital with injuries that were not life threatening. A man was arrested in connection with the assault and released without charge.
Today, around 1,000 personnel and scout volunteers were working round the clock to clear the site of stage equipment, litter and abandoned tents.
Overall, the biggest challenge to the event was the trench-like conditions brought by the rains.
Music fans emerged from their battered campsites tired but happy.
Beer and food went missing, tents were sodden and clothes were filthy, but they took it all in their stride.
Conor Ryan (25) from Newbridge stayed in the VIP camping area, which apparently was not immune to foolish pranks.
"We stayed in a tent and we were dry. One tent was robbed and partially burned. Someone burnt the lock to try to get the beer, but then it burned a little," Conor and his friend Paddy Jordan (26), from the Curragh, told the Herald.
Mary McGeown (18) from Carrickmacross in Monaghan said: "Our tent got bellyflopped twice. Someone fell on our tent, but the rain didn't put down our spirits."
Her two friends Charlene Eakins (22) and Angelica Malone (22) told the Herald: "We didn't shower but we used our baby wipes and our dry shampoo. There were girls going around looking like models and I don't know how they did it."
Caoimhe Walsh (17) from Newcastle, Co Down travelled down with Lisa Greene (17) especially for their highlight, Kings of Leon.
"Our tents were soaking last night. Me and my friend had to sleep on a chair and then eventually we got back into the tent and braved it."
Lisa Greene said: "Our tents are sodden, all my clothes were wet. Going to sleep last night I was just covered in blankets and I braved the wet tent at about 5am."
Dean Spiers (27) from Newtonards, Belfast rented a costume for the weekend which he says was his fourth Oxegen in a row.
Grainne Crowley (17) and Amy McCarthy (18) from Cork told the Herald that they missed out on all of Saturday night's performances but they had a party of their own in the campsite.
"We dropped into random tents and had parties with random people. Someone jumped on our tent and nearly killed us," says Grainne.