The Irish Blood Transfusion Service (IBTS) is warning that donations are urgently needed as blood supplies are low.
Clinics will be open on Saturday and Sunday and anyone who wishes to donate can check the IBTS website to find their nearest location.
CEO of the IBTS Andy Kelly said that low blood supplies in hospitals could affect patients.
"The knock-on effect obviously is that we would sometimes have to ration supplies to hospitals if required," he said.
"What we try to do obviously is to ensure that we have promotional activities going on which will not make that happen, and we want to ensure that the hospital services, things like patient care, elective surgeries are not in any way disrupted from a patient point of view."