The best time for scuba diving in Bangladesh is during the winter months, from October to March, when the sea is calmer and visibility is generally better. The water temperature during this time is also warmer, ranging from around 25°C (77°F) to 29°C (84°F).
During the monsoon season from June to September, the sea can be rough with strong currents, making it more difficult and potentially dangerous for scuba diving. The water can also be murkier due to the increased rainfall and runoff.
It is generally not recommended to go scuba diving in Bangladesh during the summer months from April to May, as the water can be extremely hot and uncomfortable. However, some dive operators still offer dives during this time for experienced divers who are comfortable with the conditions.