After a slight decrease from severe levels, the mercury is hovering around 40 degrees Celsius in most regions
The advisory means a storm with wind speeds between 62 and 88 kilometres per hour has formed in the distant deep sea and ships may fall into danger if they leave the harbour.
All fishing boats and trawlers over North Bay and deep sea have been advised to remain close to the coast and proceed with caution till further notice, Bangladesh Meteorological Department said in a special weather bulletin on Sunday.