The Bangladesh Meteorological Department has forecast rain or thundershowers in most parts of the country during the 120 hours starting at 9am on 5 August.
Some spells may be accompanied by temporary gusty winds, and moderate-heavy to heavy rainfall is possible in places, the department said.
The department said the monsoon is active over Bangladesh and moderate over the northern Bay of Bengal.
It said the monsoon trough extends from Rajasthan through central and northern India, West Bengal and northern Bangladesh to Assam, with a branch reaching the northern Bay of Bengal.
For the first 24 hours, rain or thundershowers are forecast in most places in all eight divisions: Rangpur, Rajshahi, Mymensingh, Dhaka, Khulna, Barishal, Chattogram and Sylhet.
Day and night temperatures may fall slightly nationwide during that period.
A similar pattern is forecast for the 24 hours beginning 9am on 6 August, with a slight decline in day and night temperatures.
For 7 August, rain or thundershowers and locally heavy rainfall remain possible in most areas, while temperatures are expected to change little.
The department forecasts continued rain or thundershowers, gusty winds in places and possible locally heavy rain for 8 August, when day and night temperatures may rise slightly.
For the 24 hours beginning 9am on 9 August, rainfall is forecast in many places in Rangpur, Rajshahi, Mymensingh and Sylhet divisions and in some places in Dhaka, Khulna, Barishal and Chattogram divisions.
Locally moderate-heavy to heavy rain may still occur on 9 August, with a slight increase in day and night temperatures forecast nationwide.
In its outlook beyond the 120-hour period, the department said the tendency for rainfall may decrease.