Although the temperatures are warm throughout the year, the hottest months on average are June and July, during which time the daily high temperatures will be in the mid 90’s. The nighttime temperatures during these months will drop to the 70’s. The coldest months of the year are December and January. During these months the daily temperatures will be in the upper 70’s, and will drop to the mid 60’s during the nights.
Generally more important to visitors than temperatures is the rain. The rainy (or monsoon) season in Hoi An is from September until January. During this time, rain clouds will constantly move through the area. There are days during which sunshine is abundant, but they are not the majority. A noticeable decrease in tourism can be seen during the wet season. The dry season is from February until May. These months provide plenty of sunshine, with warm temperatures.
All around, the best time to visit Hoi An is between May and June.
Hoi An Monsoon season & flooding
All travellers should be aware that annual monsoon season is from 1 September until mid-December 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 atleast groung floor levels of some houses in Hoi An flooded every years.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 how large they are!).