The best time to visit Hanoi is during the autumn season, which falls between September and November. During this time, the weather is mild, and the city experiences less rainfall, making it ideal for outdoor activities and sightseeing. The temperature ranges from 20-27°C (68-81°F), which is comfortable for most people.
Another good time to visit Hanoi is during the spring season, from March to April. The weather is pleasant, and the flowers are in full bloom, making the city very picturesque. The temperature ranges from 18-24°C (64-75°F), which is also comfortable for most people.
The summer months, from May to August, can be hot and humid, with temperatures ranging from 28-35°C (82-95°F). There is also a higher chance of rainfall during this time, so it might not be the best time to visit if you want to enjoy outdoor activities.
The winter months, from December to February, can be quite cold, with temperatures dropping to around 10-15°C (50-59°F). It can also be quite dry and hazy during this time, so it might not be the best time to visit if you have respiratory issues. However, if you enjoy the cooler weather, it can be a good time to visit.