Tasmania at xmas time

If I were you, I wouldn't hesitate a second - book it now ! Tassie is the perfect place to visit in January. We have been over for 3 weeks from Christmas Eve into January and almost never booked a site - there's free camps all through the forests. We did all the 4x4 treks and never saw a vehicle in those places but it was a little busy on Bruny Island, and on the NW coast, and of course booked out at Cradle Mtn - all the tourist hubs. But very quiet when you actually get into the heart of 4x4 spots.

Try this link for 11 different 4x4 Treks in Tasmania.

school holidays in Tassie at xmas is caos if possible wait till school goes back
then its beautiful
mechpete

We've been 3 times in Feb/March. Great weather, no crowds. For my money that's the best time.
Cheers

4 or 5 years ago we did 5 weeks in Tassie over December and January....about a week before Xmas we were down the Southern End of Tassie at Southport / Cockle Creek area, we were lucky to find a campsite there, but it turned out all the sites already set up on were empty of people, locals take thier vans there weeks in advance and set them up and then must come back camping after Xmas. We camped Xmas day and days either side of it at Maquarie Heads near Strahan, wasn't super busy but got more popular after Xmas day. New years we spent on the West Coast around Arthur River / Sandy Cape area, wasn't busy there at all...after N.Y. we headed North further and came across some big crowds in a camping areas there. For the most part we had no issues at all finding places to camp in that 5 weeks, rarely did we book somewhere to stay as we didn't know where we'd be, National Parks and free camps weren't ridiculously busy like the East coast mainland gets.

You will find it very busy in the school holiday period to the end of January, and I think will have trouble getting into caravan parks and national park campsites at the high profile destinations.
As others have said, from Feb through to pre-Easter is the best time, but even late autumn after Easter is good with cool but settled weather.
As a proud Tasmanian I can promise you it is a great destination, so give yourself plenty of time - don't make the mistake of thinking it's a little island you can whip around in a week or two.
Cheers

Go for it
We were there during Christmas for 4 weeks 2 years ago. We booked in for the first 3 nights at Stanley then just winged it going forward with some great free / low cost camps including Hobart showgrounds.
McQuarie heads was very nice with lots of room and we did the boat trip out of Strahan up the Gordon River.
We managed a great site at Cockle Creek for a few days, and a great spot at Friendly Beach on the East coast.
We found that arriving around mid day was the best time to find a site.
We did book in advance for Cradle Mountain.
We also bought a National Park Pass which was great value.