Bangladesh has a tropical monsoon climate. It is warm and humid. In general, the temperatures ranging from as low as 3°C during the night in the winter season to as high as 40°C in the summer season.
There are three prominent seasons:
From March to May - hot and muggy. Maximum summer temperatures range from 38 to 41°C (100.4 to 105.8 °F). In general April and May are the hottest month in most areas of the country and this is time when Bangladesh sees most of its load-shedding or power failure. So, it is better to avoid this period.
Rainy season or Monsoon:
From May to October - hot and humid. Three-quarters of the annual rainfall takes place between June and September. The average humidity of 90% to 95% in this season is uncomfortable for many people.
From November to February - warm and dry. January is the coolest month, at this time the average temperature in most of the places of Bangladesh is 16-20 °C (61-68 °F) during the day time and about 10 °C (50 °F) during the night.
Best time to visit:
For most of the people the winter season - from October to February - is the best time to visit Bangladesh. Skies are clear, days are sunny and the weather is dry. The average daytime temperature is 24 degree C. The winter season sees very small amount of rain and as a result the air becomes very dusty. So, if you have dust allergies, it would be better for you to choose the Rainy monsoon season. Lots of rain makes the air perfectly clean to breath. Another advantage of this season is the abundance of water in the low-lying areas and rivers of Bangladesh. A journey by boat in the low-lying rural areas of Bangladesh at this period of time is stunningly beautiful.