Northern Territory in December/January

Hi, I´m planning a trip to Aussi in December/January - I´ve already been there in October. I know, that in the Australien summer it is rainy season in the Northern Territory and in Queensland.
Can anybody tell me, if it´s possible to go through the Kakadu N.P. by car? Are the roads closed because of the rain? How much rain do I have to expect - all day long or only for an hour? Can I go swimming in Queensland (Cairns) or do I have to sit under an umbrella all the time?

Thanks for help!
Sylvia

Hi there,
Don't know about Kakadu or the rain, but I do know that from December to May you can't swim in the sea off Queensland unless you want a very painful death - by box Jellyfish!

Thanks for the information about this nice animal in the Queensland water. These aren´t good knews. But thank you very much for the warning.
Greetings from Germany,
Sylvia