Age Action is calling on communities to look after older peoples in their homes as the cold weather continues.
The organisation is also encouraging older people to stay in contact with friends, family and other older people.
Age Action said medical research showed that colder weather can cause blood to thicken and lead to a increased risk of stroke or heart attack.
Temperatures dropped to as low as -6C in some parts of the country overnight.
Spokesperson for Age Action Gerard Scully said elderly people should wear hats and shoes with good grips and that anyone who knows an elderly person living alone should drop in to see the person is alright.