Up to 30,000 people are expected to make the annual Croagh Patrick pilgrimage climb today.
A third of all mountain rescue volunteers from across Ireland will be on duty for the pilgrimage, the Irish Mountain Rescue Association (IMRA) said.
The pilgrims will include Archbishop Michael Neary of Tuam, commemorating how in 441 St Patrick is said to have spent 40 days and nights fasting on the summit.
"This pilgrimage has been carried out uninterrupted for over 1,500 years," a Catholic Church spokesperson said. "
"Croagh Patrick has over 100,000 visitors annually with up to 30,000 people expected this weekend."
Pilgrims are urged to bring suitable warm clothing, good footwear, a stick and water and to be mindful of the safety of themselves and others. Mountain Rescuers are also urging caution during the 2,500-foot Croagh Patrick climb.