All travellors should be aware that annual monsoon season is from 1 September until mid-December, 1st and 14th of each month (lunar calendar) at least!
Great care by all visitors should be taken during extreme rains & when there are strong onshore North East winds during lunar calendar days close to 1st or 14th - this is when danger of flooding in Hoi An and surrounding areas are highest.
BE AWARE THAT AT LEAST GROUND FLOOR LEVELS OF SOME HOUSES IN HOI AN FLOOD EVERY YEAR! Some locations such as low lying islands of Cam Nam risk is even higher of flooding.
Some street on the river banks flood and are under water for sometimes a few weeks at a time. This is a public health issue.
Cham Islands can NOT be accessed during much of the monsoon season. There are VERY few "seaworth" boats which are capable of going to Cham Islands - most boats are wooden and of flat bottom design (no matter hope large they are!).
More essential information about Hoi An at Vietnam Tour Packages
