The South is great in summer (Oct-Mar), the North is great in winter (Jun-Oct)

The North and East has summer rainfall and it's not so much about riding in rain-suites as it is about roads being closed because they're flooded (I got rained in at Halls Creek and had to wait a week for the waterlevel to drop down enough to cross Starvation creek- then had about 5 x 1m deep x 1km long water crossings to do before getting to Derby- it was pleasantly warm all the way, but everything was still under water.)

The West and South has winter rainfall. It's crap- try and stay out of it.

May is generally a good month all round.

And things like temperature is a very general term- 40C in Perth is one thing, but 35C up North is humid, stuffy and can be unbearable for some. The Central part (Alice Springs) in my experience is a dry heat and not an issue. Darwin heat (in summer) I find oppressing and hard to handle. I don't mind the cold of the South, but generally it doesn't really get cold till June.

Oh, and almost forgot- distance is also relative. you'll find some areas you'll be doing 7-800km/day relatively easily because there's not much in-between (especially central outback), and other areas, like Tasmania- 200km can take 4 hours+

I rather plan how much time I want to spend in the seat, rather than distance. But it's all relative.

But you'll love it all.

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Squily