Is December a good time to travel to South Island, New Zealand?

Is December a good time to travel to South Island, New Zealand?

I'm thinking of spending 3 weeks from mid to end December 2009 in South Island, New Zealand. Is it a good time to travel, weather-wise? Will it be crowded given that I understand it is peak season.

Question about Drive New Zealand's South Island

December is summer and school holidays, so it is going to be busier on the roads. And flights will be busier as people jet about to see family at Christmas. But it really depends your plans as to how many people you'll encounter.