Mild to moderate heat wave is sweeping Rajshahi, Dhaka, Khulna and Barishal divisions and it may continue and spread.
It is also lashing Dinajpur district and Sayedpur of Nilphamari district, said a Met office bulletin on Tuesday.
Due to excessive moisture excursion, the discomfort may increase, it said.
It also forecast rain or thunder showers accompanied by temporary gusty or squally wind at one or two places over Chattogram and Sylhet divisions with hails at isolated places.
Weather may remain mainly dry with temporary partly cloudy sky elsewhere over the country, it added.
Day temperature may remain nearly unchanged and night temperature may fall slightly over the country in 24 hours commencing 9am on Tuesday.