In general, the climate in Hoi An is mild and pleasant. The peak of summer, the temperature is at 28-33°C while the winter temperature is also quite ideal for a range of 18-23°C. Hoi An has two distinct rainy and dry seasons. Each season goes with a specific characteristic of the climate and brings different unique Hoi An which really can satisfy visitors.
Hope you can find a good suitable timing to come to Hoi An : )
1. Dry season:
From January to July
Actually, this is the ideal time to come to Hoi An. Ideally, the floor temperature will not exceed 33°C during peak sunshine, and not under 18°C during cold weather which extremely convenient for exploring all the city.
However, I highly recommend that from February to April is the best timing, with mild weather and low rainfall. Especially, this is also the time of the traditional Tet holiday (Lunar New Year) of Vietnam. Hoi An will be extremely lively with a series of festivals or cultural activities which are the most attractive things of the year. If you arrive on the occasion of the Tet Holiday, you also have the opportunity to watch Lantern Festival - a cultural symbol of Hoi An.
It's important to note that on 14th of every month (by Lunar calendar), you can see this whole city will be lightened up by small beautiful hanging lanterns. You will not want to miss that chance! For tracking the Lunar calendar, please carefully check it out for choosing the date correctly.
Quick guide: The big number you saw on that calendar followed Normal Calendar, and check the small number (below the big one) for Lunar Calendar. This is the easiest website for tracking Lunar Calendar in Vietnam. It is wrtitten by Vietnamese but I think you still can use it.
Or, you also can enjoy the floating lantern. So gorgeous, isn't it?
2. Rainy season:
Beginning in August and lasting until December
Here I will divide into 2 periods based of the level of rainfall:
2.1. From August till October
During this time, Hoi An still not too much rain so you can still enjoy all the attractions in Hoi An.
2.2. From November until January
Sometimes there are storms in this area, but its frequency is not much so you can still go to Hoi An during this time each year. In this 3 months, Hoi An has quite a lot rains so the streets will be flooded. But don't be afraid because you still can uniquely explore the city. It's worth to have the feeling of sitting on small boats and watching every corner of the ancient town.
However, as mentioned above, you should be aware of the storm and prepare both necessary things and mental for all the cases if you intend to visit Hoi An in this period. Hoi An is beautiful in every moment in its own way, in every season so that visitors can set foot and experience in the ancient city at any time. Hope with the short explanation above you can choose right timing to visit and also have a lot of good memories!