Cork Simon says last night's "cold snap" will have affected people who are sleeping rough, the most.
The charity that helps the homeless says Christmas is the most difficult time of year for people without permanent accommodation.
543 adults in Cork are currently in emergency accommodation and Cork Simon says the figures have stayed above 500 for the entire year.
Speaking to RedFM News, Paul Sheehan from Cork Simon says people living on the street find it impossible to stay warm:
"As we face into the cold days ahead now, it was almost zero degrees this morning, our biggest concern is for the people sleeping rough, no matter how many sleeping bags you have, you're sleeping on a cold concrete floor and that gets into your bones."