Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Charleston to Dhaka as you normally would.
In terms of precipitation, rainfall in Dhaka ranges from 0.3 - 14.7 inches per month. July is typically the wettest month, when rainfall can reach 14.7 in. January is typically the driest time to visit Dhaka when rainfall is around 0.3 in.
If weather is an important factor for your trip to Dhaka, use this chart to help with planning. For those seeking warmer temperatures, April is the ideal time of year to visit, when temperatures reach an average of 84.2 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 66.2 F).