Hi their, my girlfriend and i will be leaving Australia at the start of may and intend to travel to Thailand, Laos, Cambodia, Vietnam.
We would like to travel approx 4months, backpacking, working on around 30days per country, so May-August. Travelfish has a detailed itinary of the region we planned on following https://www.travelfish.org/trip_planner/thailand-indochina-tour1
My question is where should we start to make the most of these countries, without getting too affected by rain? your advice would be greatly appreciated.
You're going to get some rain.
If you start in Vietnam you'll get some good weather, but June July and August is pretty much the wet when it comes to Laos and Cambodia and parts of Thailand. Southeast Thailand (so islands like Ko Pha Ngan and Ko Samui and Ko Tao ) are pretty good though in July and August so perhaps just assume you'll get wet in the middle and have some sun at the start and the end.
Bychance we just published a story on the best beaches on KoPhaNgan -- could be useful for end of trip planning
At the end of the day, remember monsoon doesn't mean all day rain every day -- you will get some rain, most days. Some places, for eg Angkor Wat in Cambodia are lovely in the wet and the crowds are lower, so those rain clouds do have a silver lining