You plan to cover north, central and south America, Australia and southeast-Asia in 6 months? That cant be much fun, you only gonna see roads, gas stations, inside of hotelrooms or maybe your tentwalls? If I were you and had 6 months available I would do only one continent as of south America or southeast-Asia.

Central America is wet from May to October/November I think?

Andesmountains area of Peru, Bolivia, north Chile and Argentina are wet from December to April.

Southern parts of south-America aka Patagonia not very accesible from March/April to October so best travelled from Nov/Des to Febr/March.

Australia - northern parts have a heavy rainy season from November to March.
Southern parts of Australia can have pretty miserable and cold weather in June-August.

Indonesia have a rainy season from October to April so best travelled May to September.

The rest of SEAsia have a rainy season from May/June to October with some local variations of course. Best travelled November to March.

No matter what you say about rain - nobody likes to ride in heavy rain day after day after day. Your gear never get dry, your paperwork get wet, your electronical stuff stops workin etc etc. Belive me I have tried - its not fun!

And think twice about covering that much ground. I spent 6 months in Australia alone and 1,5 years in south America. And there are still many places I couldnt see or travel.

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