The Ancient Town is prone to flooding during the heaviest rains of the season which often occur in October and November, so unless you’re prepared to spend quite a bit of time indoors.
When visiting Hoi An, the main thing you need to plan for is the monsoon season. Central Vietnam’s winter monsoons typically come during the months of September to December, but it wouldn’t be uncommon for the rainy season to extend into August and January either.
The Ancient Town is prone to flooding during the heaviest rains of the season which often occur in October and November, so unless you’re prepared to spend quite a bit of time indoors, I’d avoid those months.
The driest months in Hoi An are February through July. For the most comfortable temperatures, I’d suggest planning your trip in March, April, or May. By June, temperatures soar into the high 30’s Celsius/90’s Fahrenheit, and you just might find yourself doing a little rain dance in hopes of getting some relief. And it’s possible you could get it.
We visited in mid-July when temperatures were at their highest and, despite it not being rainy season, we still had rain almost every day, some showers even lasting the entire day. Which just goes to show, you can try to avoid rainy season in Southeast Asia, but you’re never guaranteed to stay dry!