With freezing temperatures and heavy frosts, the Christchurch City Mission is urging people to donate blankets and warm clothes.

The City Mission's shelters are already packed most evenings as people try to find shelter from the cold. The Mission claims they have helped more than 11,000 people with food.

When chilly temperatures were originally forecast they stocked up but supplies are running low now, City Missioner Michael Gorman said.

"We weren't quite as unprepared as we might have been, but of course our resources are finite."

"As we give out this early in the year, we are just hopeful that we have enough for the rest of the year."

Gorman said they are seeing a huge increase in people enrolling in rehab programmes, and the main concern is the number of families and young people coming to them.

"There have been more women attending the day programmes because they want to be somewhere warm. The demand for night shelters is absolutely phenomenal. We've increased the beds to try and cope."

The City Mission's annual Paper Bag appeal launches today - with bags inserted into The Press and located at New World supermarkets.