Here's the weather forecast for Chch.
There's also an article on stuff which says:
"The rain which effects much of the North Island today or on Wednesday will have cleared away by Christmas morning," MetService public weather services manager Peter Kreft said.
Fine weather was expected to continue in the South Island with only Canterbury a possible target for the odd shower on Christmas Day, dragged in by a week southerly change.
The settled weather was expected to continue for the few days beyond Christmas Day, Mr Kreft said."