Oz weather in April-May?
 

If we go in April-May for about 6 weeks and start in the south...maybe Tasmania then work our way up towards GBR will we possibly avoid rain storms, etc? Trying to pick the time of year to visit based on what I read in guidebooks. It mentioned torrential rains floods, etc
Thanks in advance for you reply.

The northern part of Australia which is quite tropical, basically has two seasons - the wet and dry. The wet season is from about Dec - Apr and you could experience rain, high humidity, and floods.
April/May in Tasmania could be quite cold, as long as you are prepared for that, your south-north idea sounds fine.
A good weather website is www.wunderground.com
Also, at that time of year you could take your hire car (assuming you have one) for free on the Melb-Devonport ferry. Check out the Spirit of Tasmania website for sailings, passenger fares etc. If you are flying, airlines are Qantas, Virgin Blue and REX.
Kay

Well, you're out of the wet season in the north. Torrential rain anywhere else would be unusual - but never out of the question.

On the whole, this should be a fantastic time to visit. It'll be too cold to swim anywhere south of the Reef, but probably pretty good everywhere.

Generally speaking that is the best time to visit Australia both for the GBR and the southern areas.
Temperature wise you should expect say:
Cairns 30 deg Celcius max to 32
min about 19 - 21
Whitsundays a little cooler by about 2 degrees.
Tasmania would be about max 18 - 20 dec C max and about 7 min any anything in between that would be just that " anything in between"
It is very unusual to have any really heavy rains ( monsoon) around the GBR at that time of year, if it is going to happen then usually Dec, Jan, & Feb but as the weather has been strange in most areas of the world so has it here and nothing can be ruled out. Suffice it to say though that you would be coming into the peak season for the GBR at that time of year.

PS
I told you not to take too much notice of the guide books :0)

Now you're starting to get close to the mark JlW...
6 weeks working your way north is a good time frame.

It is very hard to predict the occurrence of a cyclone hitting the qld coast.The probability is low at any time of year.However if you go up there during the "wet" you will have typical tropical weather ie sauna bath heat and probably daily rain in the evening/ afternoon

You could use places like Hobart,melbourne,sydney and brisbane as hubs for a week long driving loop. get cheap flights between these cities.

You could buy a "good value" gbr and whitsunday package from sydney,melbourne or brisbane as you move around and when there was no evidence of cyclonic lows on the weather map up north.