Miranda ForsterAustralian Associated Press

Prime Minister Malcolm Turnbull has urged Australians to reach out and "give a hug" to those less fortunate this Christmas.

Mr Turnbull said he would be spending Sunday with his family, including his three grandchildren, and continuing his annual Christmas tradition of visiting Sydney's Wayside Chapel.

"It's also a very important time to reach out and give a hug to those who aren't having as happy a Christmas as you might be," he told 2GB radio on Saturday.

"You know for whatever reason - they're lonely, sick, estranged from their families. This is a season of love, and you should share it."

The prime minister said his family was shunning the traditional Christmas Day roast lunch in favour of cold dishes and fish and ham.

He downplayed his cooking abilities, describing himself as an "enthusiastic amateur".

"I've got to tell you, the rest of my family are much more talented at cooking than me," he admitted.

Mr Turnbull also paid tribute to his grandchildren, aged three, 18 months, and six months, saying they made him feel like a young man again.

"Every time I am with our grandchildren it makes me feel as though I am back in my late 20s, early 30s, and I know (my wife) Lucy feels the same," he said.