Update 2.30pm: Mayo Mountain Rescue is carrying out its usual operation on Croagh Patrick for the annual pilgrimage.
Six casualties have been treated and taken off the mountain so far today.
A man in his 70s suffered a heart attack earlier today, he was resuscitated and airlifted by Coast Guard helicopter 118 to Galway University Hospital.
A number of others received varying injuries.
Earlier: Do not let the weather fool you if you are climbing Croagh Patrick today.
Today is the annual Reek Sunday when pilgrims attempt to climb the mountain in honour of Saint Patrick.
Hundreds of rescue volunteers from mountain rescue teams across the country will be on hand for the mountain's busiest day of the year - along with 120 volunteers from the Order of Malta.
The Unit's spokesperson Aoife Clarke says you have got to be well prepared for the climb.
"What people need to remember is this is a mountain. It's not a hill, it's a mountain, so the weather conditions when you start climbing by the time you get to the top it could be completely different," she said.
"It's really important that people come prepared for every sort of weather eventuality. We'd ask people when they start to climb that they have good footwear on, good comfortable clothes, lots of layers, layers they can take off and layers that they put on, and make sure they have raingear."