I’ve been collecting info on this myself, with a view to a possible Perth to Sydney ride in a couple of years’ time. Two of my friends did the ride in 2008 in the August to October period, because the winds were said to be mostly westerly on the Nullarbor at that time of year.
One of these friends (who rode from Perth to Canberra from 26 August to 1 October) commented on his blog that “...We have been fortunate with the weather on this ride as we have not had a wet day since early in the ride at Walpole....All in all the winds have also lived up to their prediction of being predominately from the west at this time of the year.”
(see this blog entry:
http://phillstravels.blogspot.com.au/20 ... ks-29.html )
The other friend, who left Perth a few weeks later than the other one and rode to Sydney, told me that he thought that the proposition that winds on the Nullarbor are mainly from the west in September wasn’t borne out in practice for his ride. I recall him saying that he had several days or more riding into strong headwinds, as well as other days with a tailwind.
Your choice of March is within the periods recommended in the book “Bike Australia: Cycling Across Australia from Perth to Sydney” by Paul Salter (Epic Guides, NZ, first edition, 2001). But the book does note that “...March can get pretty hot”. Here’s what is said under the heading “When to Cycle Tour”:
“Summer is not the time to undertake this journey. Inland temperatures during the summer months (December through February) can be fearsome, often exceeding 40 degrees C, and on the Nullarbor, winds from the east are common. Spring (September through November) and autumn (March through May) are good times to cycle from Perth to Sydney, although March can still get very hot. Spring in particular is a good time to bike in Western Australia, the state’s wildflowers are at their best and afternoon winds from the west predominate. Winter (June to August) can be okay for bicycle touring too, although be prepared for bitterly cold nights and frequent rain.
Travelling between Perth and Sydney in spring and autumn you can expect mostly sunny days with warm to hot temperatures. Nights are cool to cold. Expect some showers, although it can rain for days on end anywhere along the route so be prepared...[the book includes monthly average temperature and rainfall data for selected towns between Perth & Sydney, which could be obtained from the BOM site]...There are about 12 hours of daylight between sunrise and sunset in springtime.”I thought I’d also mention that two commercial touring companies have chosen the July-August period to cross the Nullarbor on the Perth to Melbourne tours they are offering next year. The information provided on their websites might also be helpful in planning your daily stages:
Cycle Across Oz: Perth to Melbourne - 28 July to 2 September 2013:
http://www.cycleacrossaustralia.com/fil ... 202013.pdf All Trails:: Kalgoorlie to Adelaide sector: 18 July to 4 August 2013
http://www.alltrails.com.au/alltrails-r ... ge-10.html (click on the “Day to Day” tab to see the daily stages & distances, etc)
In case you haven't seen it, this brochure might be helpful:
http://www.transport.wa.gov.au/mediaFil ... ochure.pdf Also, I have a brochure put out by the WA and SA tourism offices called "Australia's Great Road Journey: The Nullarbor: Adelaide - Perth Adventure 2008/09" that has lots of useful information. But I couldn't find reference to a later version on either
http://www.westernaustralia.com or
http://www.southaustralia.com Anyway, hope this information is of some help.
Greg